Income Taxes (Details 6) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Changes in unrecognized income tax benefits
Unrecognized income tax benefits as of January 1	$ 28,075	$ 20,974	$ 18,131
Increases for tax positions related to
Prior years	389	14,685	1,108
Current year	913	1,447	5,667
Acquisitions	0	0	0
Decreases for tax positions related to
Prior years	(411)	(8,028)	(9)
Current year	0	0	0
Settlements with taxing authorities	(15,402)	0	(482)
Expiration of applicable statute of limitations	(76)	(1,003)	(3,441)
Unrecognized income tax benefits as of December 31	$ 13,488	$ 28,075	$ 20,974