EQUITY ROLL FORWARD (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Increase (Decrease) in Stockholders' Equity
Equity, beginning balance			$ 702,621
Net income	$ 30,039	$ 30,244	51,254	$ 46,178
Dividends on common stock			(10,658)
Common stock issued			1,795
Common stock repurchased			(10,953)
Share-based compensation			4,769
Currency translation adjustment			(25,805)
Pension liability, net of tax			1,199
Equity, ending balance	715,024		715,024
Increase (Decrease) in Temporary Equity
Temporary equity, beginning balance			1,502
Net income			(802)
Currency translation adjustment			64
Temporary equity, ending balance	764		764
Common Stock
Increase (Decrease) in Stockholders' Equity
Equity, beginning balance			4,663
Common stock issued			9
Common stock repurchased			(27)
Share-based compensation			9
Equity, ending balance	4,654		4,654
Additional Paid in Capital
Increase (Decrease) in Stockholders' Equity
Equity, beginning balance			240,136
Common stock issued			1,786
Share-based compensation			4,760
Equity, ending balance	246,682		246,682
Retained Earnings
Increase (Decrease) in Stockholders' Equity
Equity, beginning balance			604,905
Net income			51,671
Dividends on common stock			(10,658)
Common stock repurchased			(10,926)
Equity, ending balance	634,992		634,992
Minimum Pension Liability
Increase (Decrease) in Stockholders' Equity
Equity, beginning balance			(49,364)
Pension liability, net of tax			1,199
Equity, ending balance	(48,165)		(48,165)
Cumulative Translation Adjustment
Increase (Decrease) in Stockholders' Equity
Equity, beginning balance			(99,683)
Currency translation adjustment			(25,782)
Equity, ending balance	(125,465)		(125,465)
Noncontrolling Interest
Increase (Decrease) in Stockholders' Equity
Equity, beginning balance			1,964
Net income			385
Currency translation adjustment			(23)
Equity, ending balance	$ 2,326		2,326
Total Equity
Increase (Decrease) in Stockholders' Equity
Net income			$ 52,056