Income Taxes Summary of Income Tax Contingencies (Details) (USD $) In Thousands, unless otherwise specified	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]
Gross unrecognized tax benefits at beginning of year	$ 2,519	$ 1,680	$ 1,516
Increases in tax positions related to prior years	87	508	0
Decreases in tax positions for prior years	(71)	(26)	(8)
Increases in tax positions for current year	269	481	343
Settlements	(508)	0	0
Lapse in statute of limitations	(961)	(124)	(171)
Acquisitions - increase in tax position for prior years	105	0	0
Gross unrecognized tax benefits at end of year	$ 1,440	$ 2,519	$ 1,680