Property and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Plant and equipment
Property and equipment, net	$ 2,680,565		$ 2,680,565		$ 2,756,669
Decrease in property and equipment			76,100
Depreciation expense	54,400	$ 63,700	110,300	$ 128,700
Interest capitalized in connection with major construction projects	0	100	0	100
Non-leased assets
Plant and equipment
Property and equipment	2,271,478		2,271,478		2,256,017
Less Accumulated depreciation	(1,391,172)		(1,391,172)		(1,345,147)
Property and equipment, net	880,306		880,306		910,870
Land and improvements - non-leased
Plant and equipment
Property and equipment	294,716		294,716		294,695
Building and improvements - non-leased
Plant and equipment
Property and equipment	431,253		431,253		429,015
Furniture, Fixtures and Equipment
Plant and equipment
Property and equipment	1,387,069		1,387,069		1,385,889
Leasehold Improvements
Plant and equipment
Property and equipment	131,440		131,440		130,801
Construction in progress
Plant and equipment
Property and equipment	27,000		27,000		15,617
Leased assets | Master Lease Agreement
Plant and equipment
Property and equipment	2,683,277		2,683,277		2,683,277
Less Accumulated depreciation	(883,018)		(883,018)		(837,478)
Property and equipment, net	1,800,259		1,800,259		1,845,799
Depreciation expense	22,900	$ 23,000	46,200	$ 45,700
Land and improvements - leased | Master Lease Agreement
Plant and equipment
Property and equipment	424,700		424,700		424,700
Buildings and improvements - leased | Master Lease Agreement
Plant and equipment
Property and equipment	$ 2,258,577		$ 2,258,577		$ 2,258,577