Income Taxes - Components of Income Tax Expense (Benefit) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Tax Disclosure [Abstract]
Federal									$ 5,350	$ 5,662	$ 3,547
State									1,014	1,001	595
Foreign									995	1,491	740
Total current expense:									7,359	8,154	4,882
Federal									871	1,121	30
State									(343)	74	(545)
Foreign									21	482	(39)
Total deferred expense (benefit)									549	1,677	(554)
Total	$ 1,209	$ 1,811	$ 2,719	$ 2,169	$ 806	$ 2,120	$ 3,746	$ 3,159	$ 7,908	$ 9,831	$ 4,328