Stockholders' Equity - Schedule of Changes in Stockholders' Equity (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Balance	$ 666,637	$ 635,371	$ 660,417	$ 616,030
Net income	19,630	16,671	49,559	42,705
Other comprehensive income (loss)	(3,281)	(568)	(5,851)	(2,276)
Equity compensation	3,817	3,335	11,682	8,685
Exercise of stock options	1,464	2,309	1,893	5,842
Issuance of shares pursuant to vesting of restricted stock units			1
Net payments for stock issuances and buybacks	(143)	(3,802)	(24,301)	(12,399)
Dividends declared	(2,622)	(2,643)	(7,898)	(7,914)
Balance	685,502	650,673	685,502	650,673
Common Stock
Balance	$ 23	$ 22	$ 22	$ 22
Balance (in shares)	18,758	18,826	18,817	18,662
Exercise of stock options (in shares)	46	85	58	210
Issuance of shares pursuant to vesting of restricted stock units			$ 1
Issuance of shares pursuant to vesting of restricted stock units (in shares)	9	8	272	198
Net payments for stock issuances and buybacks (in shares)	(2)	(51)	(336)	(202)
Balance	$ 23	$ 22	$ 23	$ 22
Balance (in shares)	18,811	18,868	18,811	18,868
Additional Paid-in Capital
Balance	$ 335,345	$ 317,013	$ 326,208	$ 307,821
Equity compensation	3,817	3,292	11,682	8,507
Exercise of stock options	1,464	2,309	1,893	5,842
Net payments for stock issuances and buybacks		(14)	843	430
Balance	340,626	322,600	340,626	322,600
Retained Earnings
Balance	511,095	456,358	486,442	434,766
Net income	19,630	16,671	49,559	42,705
Reclassification of stranded tax effects due to adoption of accounting principle				829
Dividends declared	(2,622)	(2,643)	(7,898)	(7,914)
Balance	528,103	470,386	528,103	470,386
Treasury Stock
Balance	$ (164,705)	$ (130,446)	$ (139,704)	$ (121,540)
Balance (in shares)	3,975	3,502	3,629	3,357
Equity compensation		$ 43		$ 178
Issuance of shares pursuant to vesting of restricted stock units (in shares)		(1)		(7)
Net payments for stock issuances and buybacks	$ (143)	$ (3,788)	$ (25,144)	$ (12,829)
Net payments for stock issuances and buybacks (in shares)	2	51	348	202
Balance	$ (164,848)	$ (134,191)	$ (164,848)	$ (134,191)
Balance (in shares)	3,977	3,552	3,977	3,552
Accumulated Other Comprehensive Loss
Balance	$ (15,121)	$ (7,576)	$ (12,551)	$ (5,039)
Other comprehensive income (loss)	(3,281)	(568)	(5,851)	(2,276)
Reclassification of stranded tax effects due to adoption of accounting principle				(829)
Balance	$ (18,402)	$ (8,144)	$ (18,402)	$ (8,144)