Income Taxes (Details 4) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance, beginning of year	$ 30,949,000	$ 8,297,000	$ 5,697,000
Increases related to current year tax positions	1,225,000	2,339,000	2,528,000
Increases related to prior year tax positions	4,192,000	1,561,000	227,000
Decreases related to prior year tax positions	(4,608,000)	(11,000)	(29,000)
Acquisitions	0	25,716,000	0
Lapse of statute of limitations	(2,558,000)	(6,953,000)	0
Settlements	0	0	(126,000)
Balance, end of year	29,200,000	30,949,000	8,297,000
Unrecognized tax benefits which would affect the effective tax rate if recognized	17,500,000
Accrued interest and penalties	2,400,000
Accrued interest and penalties net of federal and state benefits	$ 2,200,000