Accumulated Other Comprehensive Income (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Reclassifications From Accumulated Other Comprehensive Income
Interest and other income (expense), net	$ (1,330)	$ (803)	$ (1,633)	$ (975)
Provision for income taxes	3,024	(4,063)	(829)	(8,369)
Net (loss) income	(4,045)	7,442	7,990	14,736
Transfers out of accumulated other comprehensive income	0
Reclassifications from accumulated other comprehensive income
Reclassifications From Accumulated Other Comprehensive Income
Net (loss) income			11
Realized gain on sale of marketable securities | Reclassifications from accumulated other comprehensive income
Reclassifications From Accumulated Other Comprehensive Income
Interest and other income (expense), net			19
Income tax benefit | Reclassifications from accumulated other comprehensive income
Reclassifications From Accumulated Other Comprehensive Income
Provision for income taxes			$ (8)