Income Taxes (Details 3) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Reconciliation of beginning and ending amount of unrecognized tax benefits
Balance at beginning of year	$ 39,425	$ 33,322	$ 30,453
Additions based on tax positions related to the current year	6,035	4,243	5,648
Additions for tax positions of prior years	7,966	3,493	993
Reductions for tax positions for prior years	(481)	(624)
Reduction for lapse in statute of limitations	(4,563)	(451)	(2,779)
Settlements	(1,537)	(558)	(993)
Balance at end of year	$ 46,845	$ 39,425	$ 33,322