2.2.0.25falsefalse1040 - Disclosure - Marketable Securitiestruefalsefalse1falsefalseUSDfalsefalse1/1/2011 - 3/31/2011 USD ($) USD ($) / shares $D2011Q1http://www.sec.gov/CIK0000875320duration2011-01-01T00:00:002011-03-31T00:00:00USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDPerShareDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0PureStandardhttp://www.xbrl.org/2003/instancepurexbrli0SharesStandardhttp://www.xbrl.org/2003/instancesharesxbrli0USDUSD$2true0vrtx_MarketableSecuritiesDisclosureAbstractvrtxfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseMarketable Securities3false0us-gaap_AvailableForSaleSecuritiesTextBlockus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1falsefalsefalse00<table style="font-size:10pt; font-family:'Times New Roman',times,serif;"> <tr> <td> D. Marketable Securities         A summary of the Company's cash, cash equivalents and marketable securities is shown below: <div style="PADDING-RIGHT: 0pt; PADDING-LEFT: 0pt; PADDING-BOTTOM: 0pt; MARGIN-LEFT: 10%; WIDTH: 80%; PADDING-TOP: 0pt; POSITION: relative">   <div align="center"> <table cellspacing="0" cellpadding="0" width="100%" border="0"> <tr style="HEIGHT: 0px"> <td style="FONT-FAMILY: times" align="left" width="9"></td> <td style="FONT-FAMILY: times" align="left"></td> <td style="FONT-FAMILY: times" width="12"></td> <td style="FONT-FAMILY: times" align="right" width="6"></td> <td style="FONT-FAMILY: times" width="53"></td> <td style="FONT-FAMILY: times" width="12"></td> <td style="FONT-FAMILY: times" align="right" width="6"></td> <td style="FONT-FAMILY: times" width="51"></td> <td style="FONT-FAMILY: times" width="12"></td> <td style="FONT-FAMILY: times" align="right" width="6"></td> <td style="FONT-FAMILY: times" width="51"></td> <td style="FONT-FAMILY: times" width="12"></td> <td style="FONT-FAMILY: times" align="right" width="6"></td> <td style="FONT-FAMILY: times" width="53"></td> <td style="FONT-FAMILY: times" width="12"></td></tr> <tr style="HEIGHT: 0px" valign="bottom"> <th style="FONT-FAMILY: times" align="left" colspan="2">  </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="2">Amortized Cost </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="2">Gross Unrealized Gains </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="2">Gross Unrealized Losses </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="2">Fair Value </th> <th style="FONT-FAMILY: times"> </th></tr> <tr style="HEIGHT: 0px" valign="bottom"> <th style="FONT-FAMILY: times" align="left" colspan="2">  </th> <th style="FONT-FAMILY: times"> </th> <th style="FONT-FAMILY: times" align="center" colspan="11">(in thousands) </th> <th style="FONT-FAMILY: times"> </th></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times" colspan="2"> March 31, 2011</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times" colspan="2"> Cash and cash equivalents</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> Cash and money market funds</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">285,890</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right"></td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right"></td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">285,890</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> U.S. Treasury securities</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">47,347</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right"></td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">(1</td> <td style="FONT-FAMILY: times">)</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">47,346</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> Government-sponsored enterprise securities</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">113,297</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">3</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right"></td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">113,300</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="FONT-SIZE: 1.5pt; HEIGHT: 0px" valign="top"> <td style="FONT-FAMILY: times" valign="bottom" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times" colspan="2"> Total cash and cash equivalents</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">446,534</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">3</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">(1</td> <td style="FONT-FAMILY: times">)</td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">446,536</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="FONT-SIZE: 1.5pt; HEIGHT: 0px" valign="top"> <td style="FONT-FAMILY: times" valign="bottom" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times" colspan="2"> Marketable securities</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> U.S. Treasury securities (due within 1 year)</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">84,703</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">12</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right"></td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">84,715</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> Government-sponsored enterprise securities (due within 1 year)</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">292,136</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">66</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">(1</td> <td style="FONT-FAMILY: times">)</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">292,201</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="FONT-SIZE: 1.5pt; HEIGHT: 0px" valign="top"> <td style="FONT-FAMILY: times" valign="bottom" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times" colspan="2"> Total marketable securities</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">376,839</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">78</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">(1</td> <td style="FONT-FAMILY: times">)</td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">376,916</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="FONT-SIZE: 1.5pt; HEIGHT: 0px" valign="top"> <td style="FONT-FAMILY: times" valign="bottom" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times" colspan="2"> Total cash, cash equivalents and marketable securities</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">823,373</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">81</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">(2</td> <td style="FONT-FAMILY: times">)</td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">823,452</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="FONT-SIZE: 1.5pt; HEIGHT: 0px" valign="top"> <td style="FONT-FAMILY: times" valign="bottom" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times" colspan="2"> December 31, 2010</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times" colspan="2"> Cash and cash equivalents</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> Cash and money market funds</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">193,845</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right"></td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right"></td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">193,845</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> U.S. Treasury securities</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">4,770</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right"></td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right"></td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">4,770</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> Government-sponsored enterprise securities</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">44,587</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">1</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">(6</td> <td style="FONT-FAMILY: times">)</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">44,582</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="FONT-SIZE: 1.5pt; HEIGHT: 0px" valign="top"> <td style="FONT-FAMILY: times" valign="bottom" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times" colspan="2"> Total cash and cash equivalents</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">243,202</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">1</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">(6</td> <td style="FONT-FAMILY: times">)</td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">243,197</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="FONT-SIZE: 1.5pt; HEIGHT: 0px" valign="top"> <td style="FONT-FAMILY: times" valign="bottom" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times" colspan="2"> Marketable securities</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> U.S. Treasury securities (due within 1 year)</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">103,230</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">1</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">(11</td> <td style="FONT-FAMILY: times">)</td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">103,220</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> Government-sponsored enterprise securities (due within 1 year)</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">684,969</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">87</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">(62</td> <td style="FONT-FAMILY: times">)</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">684,994</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="FONT-SIZE: 1.5pt; HEIGHT: 0px" valign="top"> <td style="FONT-FAMILY: times" valign="bottom" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times" colspan="2"> Total marketable securities</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">788,199</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">88</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">(73</td> <td style="FONT-FAMILY: times">)</td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">788,214</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="FONT-SIZE: 1.5pt; HEIGHT: 0px" valign="top"> <td style="FONT-FAMILY: times" valign="bottom" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times" colspan="2"> Total cash, cash equivalents and marketable securities</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">1,031,401</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">89</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">(79</td> <td style="FONT-FAMILY: times">)</td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">1,031,411</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="FONT-SIZE: 1.5pt; HEIGHT: 0px" valign="top"> <td style="FONT-FAMILY: times" valign="bottom" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td></tr></table></div> </div>         The following tables summarize the fair value and gross unrealized losses related to marketable securities, aggregated by investment category and length of time that individual securities have been in a continuous gross unrealized loss position as of March 31, 2011 and December 31, 2010: <div style="PADDING-RIGHT: 0pt; PADDING-LEFT: 0pt; PADDING-BOTTOM: 0pt; MARGIN-LEFT: 10%; WIDTH: 67%; PADDING-TOP: 0pt; POSITION: relative">   <div align="center"> <table cellspacing="0" cellpadding="0" width="120%" border="0"> <tr style="HEIGHT: 0px"> <td style="FONT-FAMILY: times" align="left" width="10"></td> <td style="FONT-FAMILY: times" align="left"></td> <td style="FONT-FAMILY: times" width="12"></td> <td style="FONT-FAMILY: times" align="right" width="7"></td> <td style="FONT-FAMILY: times" width="45"></td> <td style="FONT-FAMILY: times" width="12"></td> <td style="FONT-FAMILY: times" align="right" width="7"></td> <td style="FONT-FAMILY: times" width="51"></td> <td style="FONT-FAMILY: times" width="12"></td> <td style="FONT-FAMILY: times" align="right" width="7"></td> <td style="FONT-FAMILY: times" width="27"></td> <td style="FONT-FAMILY: times" width="12"></td> <td style="FONT-FAMILY: times" align="right" width="7"></td> <td style="FONT-FAMILY: times" width="51"></td> <td style="FONT-FAMILY: times" width="12"></td> <td style="FONT-FAMILY: times" align="right" width="7"></td> <td style="FONT-FAMILY: times" width="45"></td> <td style="FONT-FAMILY: times" width="12"></td> <td style="FONT-FAMILY: times" align="right" width="7"></td> <td style="FONT-FAMILY: times" width="51"></td> <td style="FONT-FAMILY: times" width="12"></td></tr> <tr style="HEIGHT: 0px" valign="bottom"> <th style="FONT-FAMILY: times" align="left" colspan="2">  </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="5">Less than 12 months </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="5">12 months or more </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="5">Total </th> <th style="FONT-FAMILY: times"> </th></tr> <tr style="HEIGHT: 0px" valign="bottom"> <th style="FONT-FAMILY: times" align="left" colspan="2">  </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="2">Fair Value </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="2">Gross Unrealized Loss </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="2">Fair Value </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="2">Gross Unrealized Loss </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="2">Fair Value </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="2">Gross Unrealized Loss </th> <th style="FONT-FAMILY: times"> </th></tr> <tr style="HEIGHT: 0px" valign="bottom"> <th style="FONT-FAMILY: times" align="left" colspan="2">  </th> <th style="FONT-FAMILY: times"> </th> <th style="FONT-FAMILY: times" align="center" colspan="17">(in thousands) </th> <th style="FONT-FAMILY: times"> </th></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times" colspan="2"> March 31, 2011</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times" colspan="2"> Government-sponsored enterprise securities</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">10,192</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">(1</td> <td style="FONT-FAMILY: times">)</td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right"></td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right"></td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">10,192</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">(1</td> <td style="FONT-FAMILY: times">)</td></tr> <tr style="FONT-SIZE: 1.5pt; HEIGHT: 0px" valign="top"> <td style="FONT-FAMILY: times" valign="bottom" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> Total</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">10,192</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">(1</td> <td style="FONT-FAMILY: times">)</td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right"></td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right"></td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">10,192</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">(1</td> <td style="FONT-FAMILY: times">)</td></tr> <tr style="FONT-SIZE: 1.5pt; HEIGHT: 0px" valign="top"> <td style="FONT-FAMILY: times" valign="bottom" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td></tr></table></div> </div>   <div style="PADDING-RIGHT: 0pt; PADDING-LEFT: 0pt; PADDING-BOTTOM: 0pt; MARGIN-LEFT: 10%; WIDTH: 67%; PADDING-TOP: 0pt; POSITION: relative">   <div align="center"> <table cellspacing="0" cellpadding="0" width="120%" border="0"> <tr style="HEIGHT: 0px"> <td style="FONT-FAMILY: times" align="left" width="10"></td> <td style="FONT-FAMILY: times" align="left"></td> <td style="FONT-FAMILY: times" width="12"></td> <td style="FONT-FAMILY: times" align="right" width="7"></td> <td style="FONT-FAMILY: times" width="51"></td> <td style="FONT-FAMILY: times" width="12"></td> <td style="FONT-FAMILY: times" align="right" width="7"></td> <td style="FONT-FAMILY: times" width="51"></td> <td style="FONT-FAMILY: times" width="12"></td> <td style="FONT-FAMILY: times" align="right" width="7"></td> <td style="FONT-FAMILY: times" width="27"></td> <td style="FONT-FAMILY: times" width="12"></td> <td style="FONT-FAMILY: times" align="right" width="7"></td> <td style="FONT-FAMILY: times" width="51"></td> <td style="FONT-FAMILY: times" width="12"></td> <td style="FONT-FAMILY: times" align="right" width="7"></td> <td style="FONT-FAMILY: times" width="51"></td> <td style="FONT-FAMILY: times" width="12"></td> <td style="FONT-FAMILY: times" align="right" width="7"></td> <td style="FONT-FAMILY: times" width="51"></td> <td style="FONT-FAMILY: times" width="12"></td></tr> <tr style="HEIGHT: 0px" valign="bottom"> <th style="FONT-FAMILY: times" align="left" colspan="2">  </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="5">Less than 12 months </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="5">12 months or more </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="5">Total </th> <th style="FONT-FAMILY: times"> </th></tr> <tr style="HEIGHT: 0px" valign="bottom"> <th style="FONT-FAMILY: times" align="left" colspan="2">  </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="2">Fair Value </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="2">Gross Unrealized Loss </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="2">Fair Value </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="2">Gross Unrealized Loss </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="2">Fair Value </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="2">Gross Unrealized Loss </th> <th style="FONT-FAMILY: times"> </th></tr> <tr style="HEIGHT: 0px" valign="bottom"> <th style="FONT-FAMILY: times" align="left" colspan="2">  </th> <th style="FONT-FAMILY: times"> </th> <th style="FONT-FAMILY: times" align="center" colspan="17">(in thousands) </th> <th style="FONT-FAMILY: times"> </th></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times" colspan="2"> December 31, 2010</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times" colspan="2"> U.S. Treasury securities</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">95,942</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">(11</td> <td style="FONT-FAMILY: times">)</td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right"></td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right"></td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">95,942</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">(11</td> <td style="FONT-FAMILY: times">)</td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times" colspan="2"> Government-sponsored enterprise securities</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">253,871</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">(62</td> <td style="FONT-FAMILY: times">)</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right"></td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right"></td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">253,871</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">(62</td> <td style="FONT-FAMILY: times">)</td></tr> <tr style="FONT-SIZE: 1.5pt; HEIGHT: 0px" valign="top"> <td style="FONT-FAMILY: times" valign="bottom" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> Total</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">349,813</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">(73</td> <td style="FONT-FAMILY: times">)</td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right"></td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right"></td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">349,813</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">(73</td> <td style="FONT-FAMILY: times">)</td></tr> <tr style="FONT-SIZE: 1.5pt; HEIGHT: 0px" valign="top"> <td style="FONT-FAMILY: times" valign="bottom" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td></tr></table></div> </div>         In the three months ended March 31, 2011 and 2010, the Company had proceeds of $536.4 million and $184.3 million, respectively, from sales and maturities of available-for-sale securities.         Realized gains and losses are determined using the specific identification method and are included in interest income on the condensed consolidated statements of operations. There were no gross realized gains and losses for the three months ended March 31, 2011 and 2010. </td></tr></table> D. Marketable Securities         A summary of the Company's cash, cash equivalents and marketable securities is shownfalsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringThis item represents the entire disclosure related to Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Emerging Issues Task Force (EITF) -Number 03-1 -Paragraph 21 -Subparagraph a, b Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number FAS115-1/124-1 -Paragraph 17 -Subparagraph a, b Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 19, 20, 21 falsefalseMarketable Securities12Marketable SecuritiesUnKnownUnKnownUnKnownUnKnownfalsetrue