Revenue from Contracts with Customers - Impact of Adoption of New Accounting Principle (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Jan. 01, 2018	Dec. 31, 2017
Condensed Consolidated Statements of Financial Position:
Inventory	$ 107,935			$ 112,557
Retained earnings	714,888			684,540
Condensed Consolidated Statement of Income
Net sales	214,611	$ 203,828
Cost of sales	138,005	123,478
Income tax expense	4,771	12,885
Net income	$ 26,136	$ 27,032
Basic earnings per share (in dollars per share)	$ 1.43	$ 1.50
Diluted earnings per share (in dollars per share)	$ 1.40	$ 1.47
Condensed Consolidated Statement of Cash Flows:
Deferred income taxes	$ 1,342	$ 3,516
Contract assets	(22,040)	0
Inventories	5,813	(769)
Other, net	6,355	742
Net cash provided by operating activities	8,768	$ 23,234
Accounting Standards Update 2014-09
Condensed Consolidated Statements of Financial Position:
Contract assets	22,040		$ 18,099
Inventory	107,935		100,250
Deferred income taxes	13,086		12,286
Retained earnings	714,888		688,752
Under ASC 605
Condensed Consolidated Statement of Income
Net sales	210,670
Cost of sales	135,325
Income tax expense	4,438
Net income	$ 25,208
Basic earnings per share (in dollars per share)	$ 1.38
Diluted earnings per share (in dollars per share)	$ 1.35
Condensed Consolidated Statement of Cash Flows:
Deferred income taxes	$ (571)
Contract assets	0
Inventories	(9,174)
Other, net	2,143
Net cash provided by operating activities	8,768
Under ASC 605 | Accounting Standards Update 2014-09
Condensed Consolidated Statements of Financial Position:
Contract assets	0			0
Inventory	122,922			112,557
Deferred income taxes	11,173			10,706
Retained earnings	709,748			$ 684,540
Impact of Adoption
Condensed Consolidated Statement of Income
Net sales	3,941
Cost of sales	2,680
Income tax expense	333
Net income	$ 928
Basic earnings per share (in dollars per share)	$ 0.05
Diluted earnings per share (in dollars per share)	$ 0.05
Condensed Consolidated Statement of Cash Flows:
Deferred income taxes	$ 1,913
Contract assets	(22,040)
Inventories	14,987
Other, net	4,212
Net cash provided by operating activities	0
Impact of Adoption | Accounting Standards Update 2014-09
Condensed Consolidated Statements of Financial Position:
Contract assets	22,040		18,099
Inventory	(14,987)		(12,307)
Deferred income taxes	1,913		1,580
Retained earnings	$ 5,140		$ 4,212