Income Taxes (Details 6) (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 at beginning of year	$ 9,378,000	$ 6,148,000	$ 5,586,000
Additions based on tax positions related to the prior years	4,172,000	3,230,000	562,000
Unrecognized Tax Benefits, Decreases Resulting from Settlements with Taxing Authorities	(2,344,000)	0	0
Balance at end of year	11,206,000	9,378,000	6,148,000
Unrecognized tax benefits highly certain deductibility	6,600,000	3,800,000
Unrecognized tax benefits that would affect the effective tax rate	6,000,000	7,100,000
Unrecognized tax benefits, interest and penalties	1,400,000	1,500,000
Interest expense	780,000	2,000,000	190,000
Interest income	1,900,000	20,000	165,000
Accrued liability for payment of interest	$ 970,000	$ 2,300,000