Stockholders' Equity - Schedule of Changes in Stockholders' Equity (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Balance	$ 662,571	$ 622,501	$ 660,417	$ 616,030
Net income	14,611	13,617	29,929	26,034
Other comprehensive income	(2,853)	(3,317)	(2,570)	(1,708)
Equity compensation	3,714	2,959	7,865	5,350
Exercise of stock options	25	1,733	429	3,533
Issuance of shares pursuant to vesting of restricted stock units			1
Net payments for stock issuances and buybacks	(8,789)	512	(24,158)	(8,597)
Dividends declared	(2,642)	(2,634)	(5,276)	(5,271)
Balance	666,637	635,371	666,637	635,371
Common Stock
Balance	$ 23	$ 22	$ 22	$ 22
Balance (in shares)	18,866	18,767	18,817	18,662
Exercise of stock options (in shares)	1	49	12	125
Issuance of shares pursuant to vesting of restricted stock units			$ 1
Issuance of shares pursuant to vesting of restricted stock units (in shares)	8	3	263	190
Net payments for stock issuances and buybacks (in shares)	(117)	7	(334)	(151)
Balance	$ 23	$ 22	$ 23	$ 22
Balance (in shares)	18,758	18,826	18,758	18,826
Additional Paid-in Capital
Balance	$ 330,763	$ 311,941	$ 326,208	$ 307,821
Equity compensation	3,714	2,895	7,865	5,215
Exercise of stock options	25	1,733	429	3,533
Net payments for stock issuances and buybacks	843	444	843	444
Balance	335,345	317,013	335,345	317,013
Retained Earnings
Balance	499,126	445,375	486,442	434,766
Net income	14,611	13,617	29,929	26,034
Reclassification of stranded tax effects due to adoption of accounting principle				829
Dividends declared	(2,642)	(2,634)	(5,276)	(5,271)
Balance	511,095	456,358	511,095	456,358
Treasury Stock
Balance	$ (155,073)	$ (130,578)	$ (139,704)	$ (121,540)
Balance (in shares)	3,846	3,512	3,629	3,357
Equity compensation		$ 64		$ 135
Issuance of shares pursuant to vesting of restricted stock units (in shares)		(3)		(6)
Net payments for stock issuances and buybacks	$ (9,632)	$ 68	$ (25,001)	$ (9,041)
Net payments for stock issuances and buybacks (in shares)	129	(7)	346	151
Balance	$ (164,705)	$ (130,446)	$ (164,705)	$ (130,446)
Balance (in shares)	3,975	3,502	3,975	3,502
Accumulated Other Comprehensive Loss
Balance	$ (12,268)	$ (4,259)	$ (12,551)	$ (5,039)
Other comprehensive income	(2,853)	(3,317)	(2,570)	(1,708)
Reclassification of stranded tax effects due to adoption of accounting principle				(829)
Balance	$ (15,121)	$ (7,576)	$ (15,121)	$ (7,576)