Income Taxes (Details 3) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Reconciliation of unrecognized tax benefits
Balance at the beginning of the period	$ 5,862,000	$ 6,422,000	$ 6,705,000
Additions based on tax positions related to prior years	18,000	1,236,000	640,000
Reductions based on tax positions related to prior years	(681,000)	(537,000)	(632,000)
Additions for tax positions of the current year	570,000	951,000	902,000
Settlements	(362,000)	(59,000)
Lapse of statute of limitations	(724,000)	(2,151,000)	(1,193,000)
Balance at the end of the period	4,683,000	5,862,000	6,422,000
Portion of uncertain tax benefit, if recognized, would reduce effective tax rate	1,100,000	1,200,000	1,500,000
Decrease in accrued interest as a result of the reversal of accrued interest associated with the lapse of statutes of limitations	48,000	463,000	88,000
Accrued interest	$ 1,100,000	$ 1,100,000	$ 1,600,000