Net Income Per Share - Contingently Issuable Equity Awards (Details) (Options to Purchase Shares of Common Stock and Restricted Stock Awards [Member], Contingently Issuable Shares [Member]) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Options to Purchase Shares of Common Stock and Restricted Stock Awards [Member] | Contingently Issuable Shares [Member]
Contingently Issuable Equity Awards Excluded from Computation of Earnings Per Share [Line Items]
Contingently issuable equity awards	716	356	716	356