Income Taxes - Current and Deferred (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current:
Federal									$ 5,731	$ 4,802	$ 2,628
State									(1,645)	4,823	1,634
Foreign									12,647	9,449	4,657
Total									16,733	19,074	8,919
Deferred:
Federal									13,665	(4,701)	1,606
State									2,570	1,026	992
Foreign									(3,312)	(1,304)	453
Total									12,923	(4,979)	3,051
Total, income tax expense (benefit)	$ 22,308	$ 480	$ 1,261	$ 5,607	$ 4,820	$ 713	$ 3,762	$ 4,800	29,656	14,095	11,970
Components of income (loss) before income taxes
U.S.									51,797	15,779	15,687
Foreign									69,429	49,208	27,368
Income before income tax expense	104,645	$ 3,190	$ (8,949)	$ 22,340	17,801	$ 12,078	$ 16,688	$ 18,420	121,226	64,987	$ 43,055
Deferred tax assets:
Compensation and benefits	13,742				17,252				13,742	17,252
Net operating loss and capital loss carryover	16,094				16,949				16,094	16,949
Share-based compensation	6,488				7,719				6,488	7,719
Allowance for doubtful accounts	396				452				396	452
Tax benefits on uncertain tax positions	2,862				3,507				2,862	3,507
Goodwill and other intangibles	9,483				16,256				9,483	16,256
Other	7,736				8,568				7,736	8,568
Total deferred tax assets	56,801				70,703				56,801	70,703
Less: valuation allowance	19,444				20,400				19,444	20,400
Total deferred tax assets, net of valuation allowance	37,357				50,303				37,357	50,303
Deferred tax liabilities:
Depreciation	(1,281)				(1,575)				(1,281)	(1,575)
Capitalized software	(12,072)				(11,870)				(12,072)	(11,870)
Other	(414)				(352)				(414)	(352)
Total deferred tax liabilities	(13,767)				(13,797)				(13,767)	(13,797)
Net deferred tax assets	$ 23,590				$ 36,506				$ 23,590	$ 36,506