Consolidated Statements of Equity - USD ($) $ in Thousands		Total		Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income/(Loss)	Treasury Stock	Non - Controlling Interest
Beginning balance (in shares) at Dec. 31, 2015				34,781,201				1,689,978
Beginning balance at Dec. 31, 2015		$ 465,771		$ 35	$ 254,052	$ 320,989	$ (67,325)	$ (42,159)	$ 179
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock issued, stock-based compensation plans (in shares)				918,618
Stock issued, stock-based compensation plans		6,499		$ 1	6,498
Stock issued, business acquisition	[1]	0
Stock-based compensation		19,770			19,770
Excess tax benefit from stock based compensation		4,326			4,326
Acquisition of treasury stock (in shares)								(381,732)
Acquisition of treasury stock		(18,203)						$ (18,203)
Non-controlling interest		14							14
Other comprehensive loss		(7,732)					(7,732)
Net income		61,733	[1],[2]			61,733
Ending balance (in shares) at Dec. 31, 2016				35,699,819				2,071,710
Ending balance at Dec. 31, 2016		532,178		$ 36	284,646	382,722	(75,057)	$ (60,362)	193
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Impact on adoption of accounting standard update	[3]	1,453			5,999	(4,546)
Beginning balance, adjusted		533,631		$ 36	290,645	378,176	(75,057)	$ (60,362)	193
Stock issued, stock-based compensation plans (in shares)				1,090,932
Stock issued, stock-based compensation plans		8,561		$ 1	8,560
Stock issued, business acquisition	[1]	0
Stock-based compensation		23,041			23,041
Acquisition of treasury stock (in shares)								(830,308)
Acquisition of treasury stock		(43,454)						$ (43,454)
Non-controlling interest		31							31
Other comprehensive loss		29,347					29,347
Net income		$ 48,888	[1],[2]			48,888
Ending balance (in shares) at Dec. 31, 2017		33,888,733		36,790,751				2,902,018
Ending balance at Dec. 31, 2017		$ 600,045		$ 37	322,246	427,064	(45,710)	$ (103,816)	224
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Impact on adoption of accounting standard update	[4]	454				454
Beginning balance, adjusted		600,499		$ 37	322,246	427,518	(45,710)	$ (103,816)	224
Stock issued, stock-based compensation plans (in shares)				990,334
Stock issued, stock-based compensation plans		1,398		$ 1	1,397
Stock issued business acquisition (in shares)				69,459
Stock issued, business acquisition		4,080			4,080
Stock-based compensation		23,901			23,901
Acquisition of treasury stock (in shares)								(726,050)
Acquisition of treasury stock		(43,109)						$ (43,109)
Allocation of equity component related to the convertible senior notes, net of tax and issuance costs		12,555			12,555
Non-controlling interest		26							26
Other comprehensive loss		(37,757)					(37,757)
Net income		$ 56,726				56,726
Ending balance (in shares) at Dec. 31, 2018		34,222,476		37,850,544				3,628,068
Ending balance at Dec. 31, 2018		$ 618,319		$ 38	$ 364,179	$ 484,244	$ (83,467)	$ (146,925)	$ 250

[1] Adjusted pursuant to adoption of ASU 2016-18, Statements of Cash Flows, Restricted Cash. Refer to Note 8 and Note 27 to the consolidated financial statements.

[2] Adjusted pursuant to adoption of ASU No. 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Post-retirement Benefit Cost. Refer to Note 21 and Note 27 to the consolidated financial statements.

[3] Refer to Note 2(p) to the consolidated financial statements for details.

[4] Refer to Note 2(d) to the consolidated financial statements for details.