Equity - Changes in AOCI/L by Component (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 983,465
Other comprehensive income, net of tax	30,717	$ 1,851
Ending balance	987,571
Interest Rate Swaps
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	2,483	(1,409)
Change in AOCI/L before reclassifications to income	9,365	(3,393)
Reclassifications from AOCL/I to income during the period	749	825
Other comprehensive income, net of tax	10,114	(2,568)
Ending balance	12,597	(3,977)
Defined Benefit Pension Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(5,861)	(5,797)
Change in AOCI/L before reclassifications to income	0	0
Reclassifications from AOCL/I to income during the period	56	48
Other comprehensive income, net of tax	56	48
Ending balance	(5,805)	(5,749)
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	4,886	(42,477)
Change in AOCI/L before reclassifications to income	20,547	4,371
Reclassifications from AOCL/I to income during the period	0	0
Other comprehensive income, net of tax	20,547	4,371
Ending balance	25,433	(38,106)
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	1,508	(49,683)
Change in AOCI/L before reclassifications to income	29,912	978
Reclassifications from AOCL/I to income during the period	805	873
Other comprehensive income, net of tax	30,717	1,851
Ending balance	$ 32,225	$ (47,832)