Fair Value Measurements - Goodwill and Asset Impairment (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill and asset impairment	$ 37,927,000	$ 5,500,000	$ 16,103,000	$ 430,363,000	$ 18,966,000	$ 368,551,000	$ 1,559,000	$ 20,706,000	$ 489,893,000	$ 409,782,000	$ 248,515,000
Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill (Note 8)									351,700,000	205,000,000	0
Property, plant and equipment and leasehold intangibles, net (Note 7)									78,000,000	164,400,000	166,200,000
Investment in unconsolidated ventures (Note 6)									33,400,000	25,800,000	36,800,000
Other intangible assets, net (Note 8)									9,100,000	14,600,000	29,700,000
Assets held for sale (Note 4)									15,600,000	0	15,800,000
Other intangible assets, net (Note 8)									2,100,000	0	0
Goodwill and asset impairment									$ 489,900,000	$ 409,800,000	$ 248,500,000