Borrowings (Narrative) (Details) (USD $)	3 Months Ended			1 Months Ended	3 Months Ended
	Mar. 31, 2013 item	Mar. 31, 2012	Dec. 31, 2012	Nov. 30, 2011 Institutional And Accredited Investor [Member]	Mar. 31, 2013 Institutional And Accredited Investor [Member]	Mar. 31, 2013 Loss On Conversion Of Notes [Member]
Debt Instrument [Line Items]
Interest rate				5.50%
Private placement of senior convertible notes	$ 48,340,000		$ 90,960,000	$ 152,000,000
Issuance costs	6,634,000
Proceeds from issuance of notes	145,366,000
Converted number of common stock shares	69.9032
Initial conversion rate	$ 14.31
Amount of notes converted	42,060,000
Common stock converted, shares	2,979,000
Loss on conversion of convertible debt	5,715,000
Interest and other expense, net	10,067,000	2,682,000				5,715,000
Debt instrument periodic payment				payable in cash semi-annually on June 15 and December 15 of each year
Convertible Senior Notes principal amount	$ 1
Number shares that the notes are convertible	3,379,000
Maturity date					Dec. 15, 2016
Notes issued with an effective yield	5.96%
Original issue discount	98.00%
Redeemable convertible securities maximum, shares	4,308,000
Redeemable convertible securities price per share	$ 11.22