Shareholders' Equity and Partners' Capital - Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2019	Mar. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	$ 6,716,917	$ 5,845,506
Balance	6,386,532	6,716,917
AOCI Attributable to Parent
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	54	4,208
Balance	(9,696)	54
MGP Operating Partnership
Accumulated Other Comprehensive Income (Loss) [Line Items]
Issuance of Operating Partnership units		548,391
MGP Operating Partnership | Limited Partners
Accumulated Other Comprehensive Income (Loss) [Line Items]
Issuance of Operating Partnership units		548,391
Empire City | MGP Operating Partnership
Accumulated Other Comprehensive Income (Loss) [Line Items]
Acquisitions		379,050
Empire City | MGP Operating Partnership | Limited Partners
Accumulated Other Comprehensive Income (Loss) [Line Items]
Acquisitions		379,050
Park MGM Lease Transaction | MGP Operating Partnership
Accumulated Other Comprehensive Income (Loss) [Line Items]
Acquisitions		31,875
Park MGM Lease Transaction | MGP Operating Partnership | Limited Partners
Accumulated Other Comprehensive Income (Loss) [Line Items]
Acquisitions		31,875
Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance		4,208
Other comprehensive income before reclassifications	(42,773)
Amounts reclassified from accumulated other comprehensive income to interest expense	(3,614)
Less: Other comprehensive income	(45,927)
Balance	(9,696)
Other Comprehensive Income (Loss) | AOCI Attributable to Parent
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance		$ 4,208
Balance	(10,156)
Other Comprehensive Income (Loss) | Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income before reclassifications	(42,773)
Amounts reclassified from accumulated other comprehensive income to interest expense	(3,614)
Less: Other comprehensive income	(46,387)
Other Comprehensive Income (Loss) | AOCI Attributable to Noncontrolling Interest
Accumulated Other Comprehensive Income (Loss) [Line Items]
Less: Other comprehensive income	32,023
Other Comprehensive Income (Loss) | Limited Partners
Accumulated Other Comprehensive Income (Loss) [Line Items]
Less: Other comprehensive income	460
Balance	460
Other Comprehensive Income (Loss) | MGP Operating Partnership
Accumulated Other Comprehensive Income (Loss) [Line Items]
Issuance of Operating Partnership units	669
Other Comprehensive Income (Loss) | MGP Operating Partnership | Limited Partners
Accumulated Other Comprehensive Income (Loss) [Line Items]
Issuance of Operating Partnership units	669
Other Comprehensive Income (Loss) | Empire City | MGP Operating Partnership
Accumulated Other Comprehensive Income (Loss) [Line Items]
Acquisitions	(195)
Other Comprehensive Income (Loss) | Empire City | MGP Operating Partnership | Limited Partners
Accumulated Other Comprehensive Income (Loss) [Line Items]
Acquisitions	(195)
Other Comprehensive Income (Loss) | Park MGM Lease Transaction | MGP Operating Partnership
Accumulated Other Comprehensive Income (Loss) [Line Items]
Acquisitions	(16)
Other Comprehensive Income (Loss) | Park MGM Lease Transaction | MGP Operating Partnership | Limited Partners
Accumulated Other Comprehensive Income (Loss) [Line Items]
Acquisitions	(16)
Other Comprehensive Income (Loss) | Northfield OpCo | MGP Operating Partnership
Accumulated Other Comprehensive Income (Loss) [Line Items]
Acquisitions	2
Other Comprehensive Income (Loss) | Northfield OpCo | MGP Operating Partnership | Limited Partners
Accumulated Other Comprehensive Income (Loss) [Line Items]
Acquisitions	$ 2