Fair Value Measurements - Goodwill and Asset Impairment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill	$ 351,652
Goodwill and asset impairment	430,363	$ 20,706
Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill	351,700	0
Property, plant and equipment and leasehold intangibles, net	40,800	1,000
Investment in unconsolidated ventures	33,400	19,700
Other intangible assets, net	1,700	0
Assets held for sale	2,800	0
Goodwill and asset impairment	$ 430,400	$ 20,700