Debt Narratives (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Debt Instrument [Line Items]
Document Period End Date			Jun. 30, 2019
Debt, Weighted Average Interest Rate	4.94%		4.94%		4.99%
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate	77.00%		77.00%		66.00%
Interest Paid, Including Capitalized Interest, Operating and Investing Activities			$ 97,300	$ 89,100
Bank Credit Facility	$ 0		0		$ 387,061
Term Loan	700,000		700,000
Letters of Credit Outstanding, Amount	32,900		$ 32,900
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage			0.20%
Line of Credit Facility, Remaining Borrowing Capacity	967,100		$ 967,100
Line of Credit Facility, Increase (Decrease), Net			55,000
Repayments of Long-term Debt			8,712	8,631
Loss on early extinguishment of debt, net	(7,579)	$ 0	(7,579)	(10,131)
Repayments of Debt			836,800	268,200
Repayments of Long-term Capital Lease Obligations			21,807	19,270
Redemption Premium	4,300
Letters of Credit Limit	100,000		100,000
Proceeds from Issuance of Debt			854,300
December 2022
Debt Instrument [Line Items]
Bank Credit Facility	0		0
Term Loan	650,000		650,000		0
Letters of Credit Outstanding, Amount					395,000
Redemption Premium				9,600
Term Loan [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Increase (Decrease), Net	17,200
Repayments of Debt	32,100		40,500
Redemption Premium				8,400
Proceeds from Issuance of Debt	49,300
October 2018
Debt Instrument [Line Items]
Line of Credit Facility, Increase (Decrease), Net				370,000
Repayments of Long-term Debt				$ 250,000
Bank Credit Facility due March 2022 [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity	1,000,000		1,000,000
Repayments of Debt			450,000
Other Debt [Member]
Debt Instrument [Line Items]
Repayments of Debt			200
Line of Credit Facility, Maximum Borrowing Capacity	1,700,000		1,700,000
Unsecured Debt | May 2024
Debt Instrument [Line Items]
Senior Notes	850,000		850,000		850,000
Unsecured Debt | June 2029 [Member]
Debt Instrument [Line Items]
Senior Notes	$ 750,000		$ 750,000		$ 0