Income Taxes (Details 3) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Reconciliation of unrecognized tax benefits
Balance at the beginning of the period	$ 4,683,000	$ 5,862,000	$ 6,422,000
Additions based on tax positions related to prior years	527,000	18,000	1,236,000
Reductions based on tax positions related to prior years	(1,163,000)	(681,000)	(537,000)
Additions for tax positions of the current year	933,000	570,000	951,000
Settlements	(486,000)	(362,000)	(59,000)
Lapse of statute of limitations	(651,000)	(724,000)	(2,151,000)
Balance at the end of the period	3,843,000	4,683,000	5,862,000
Portion of uncertain tax benefit, if recognized, would reduce effective tax rate	900,000	1,100,000	1,200,000
Decrease in accrued interest as a result of the reversal of accrued interest associated with the lapse of statutes of limitations	400,000	0	500,000
Accrued interest	$ 700,000	$ 1,100,000	$ 1,100,000