Fair Value Measurements (Details 5) (ARS, USD $)	3 Months Ended
	Mar. 31, 2012 item	Mar. 31, 2013	Dec. 31, 2012
ARS
Changes in Level 3 assets measured at fair value on recurring basis
Beginning balance	$ 62,311,000	$ 46,283,000	$ 46,283,000
Settlements	(16,553,000)
Realized loss included in other income (expense), net	(2,699,000)
Reversal of pretax impairment charges included in accumulated other comprehensive income (loss)	3,224,000
Ending balance	46,283,000	46,283,000	46,283,000
Number of auction rate securities sold or redeemed for full par value	1
Number of auction rate securities (ARS) sold in a secondary market	2
Number of auction rate securities (ARS) settled	3
Pre-tax gain on securities redeemed	$ 2,700,000