Stockholders' Equity - Schedule of Changes in Stockholders' Equity (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Balance	$ 660,417	$ 616,030
Net income	15,318	12,417
Other comprehensive income	283	1,609
Equity compensation	4,151	2,391
Exercise of stock options	404	1,800
Issuance of shares pursuant to vesting of stock units	1
Net payments for stock issuances and buybacks	(15,369)	(9,109)
Dividends declared	(2,634)	(2,637)
Balance	662,571	622,501
Common Stock
Balance	$ 22	$ 22
Balance (in shares)	18,817	18,662
Exercise of stock options (in shares)	11	76
Issuance of shares pursuant to vesting of stock units	$ 1
Issuance of shares pursuant to vesting of stock units (in shares)	255	187
Net payments for stock issuances and buybacks (in shares)	(217)	(158)
Balance	$ 23	$ 22
Balance (in shares)	18,866	18,767
Additional Paid-in Capital
Balance	$ 326,208	$ 307,821
Equity compensation	4,151	2,320
Exercise of stock options	404	1,800
Balance	330,763	311,941
Retained Earnings
Balance	486,442	434,766
Net income	15,318	12,417
Reclassification of stranded tax effects due to adoption of accounting principle		829
Dividends declared	(2,634)	(2,637)
Balance	499,126	445,375
Treasury Stock
Balance	$ (139,704)	$ (121,540)
Balance (in shares)	3,629	3,357
Equity compensation		$ 71
Issuance of shares pursuant to vesting of stock units (in shares)		(3)
Net payments for stock issuances and buybacks	$ (15,369)	$ (9,109)
Net payments for stock issuances and buybacks (in shares)	217	158
Balance	$ (155,073)	$ (130,578)
Balance (in shares)	3,846	3,512
Accumulated Other Comprehensive Loss
Balance	$ (12,551)	$ (5,039)
Other comprehensive income	283	1,609
Reclassification of stranded tax effects due to adoption of accounting principle		(829)
Balance	$ (12,268)	$ (4,259)