Supplemental Balance Sheet, Income Statement and Cash Flow Information - Acquisitions of Businesses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Supplemental cash flow information
Cash paid for income taxes	$ 20,581	$ 34,479	$ 66,910
Cash paid for interest, net of capitalized interest	191,986	184,445	168,979
Net change in accounts payable related to capital expenditures	(35,227)	22,920	(59,565)
Net change in assets related to increase in redeemable noncontrolling interest in subsidiary	142,875
Acquisitions of businesses:
Fair value of assets acquired	280,709		327,857
Goodwill	5,690		86,502
Liabilities assumed	(55,742)		(306,084)
Gain on acquisition			(2,308)
Shares issuance as consideration (non-cash financing activity)	(178,993)
Payments on future consideration		22,278	22,278
Cash paid for acquisitions of businesses	51,664	22,278	128,245
Cash acquired in acquisitions of businesses	(60,704)		(48,058)
Cash paid for acquisition of businesses, net of cash acquired	$ 9,040	$ (22,278)	$ (80,187)