Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 254,326	$ 556,778	$ 141,096
OTHER COMPREHENSIVE (LOSS)/INCOME:
Foreign currency translation adjustment	(93,158)	106,861	(47,349)
Net unrealized gain/(loss) on qualifying cash flow hedges, net of tax (provision)/benefit	720	1,870	(5,666)
Changes in pension and other postretirement benefit obligations, net of tax (provision)/benefit	30,853	347	(30,953)
Other comprehensive (loss)/income	(61,585)	109,078	(83,968)
COMPREHENSIVE INCOME	192,741	665,856	57,128
Less: Comprehensive (loss)/income attributable to noncontrolling interest	(13,725)	25,023	8,508
COMPREHENSIVE INCOME ATTRIBUTABLE TO G&W	$ 206,466	$ 640,833	$ 48,620