Business - Narrative (Details) - USD ($) $ in Millions					6 Months Ended
	Apr. 01, 2019	Mar. 07, 2019	Jan. 29, 2019	Jul. 06, 2018	Jun. 30, 2019	Apr. 02, 2019	Mar. 30, 2019	Jan. 09, 2019	Dec. 31, 2018
Business And Organization [Line Items]
Ownership percentage acquired ( as a percent )					31.70%
Rent payments due under master lease						$ 946.1	$ 770.3
Empire City
Business And Organization [Line Items]
Business Acquisition, Transaction Costs			$ 634.4
Rent payments due under master lease								$ 50.0
Park MGM Lease Transaction
Business And Organization [Line Items]
Business Acquisition, Transaction Costs		$ 637.5
Business Combination, Consideration Transferred, Other		605.6
Rent payments due under master lease		$ 50.0
Northfield
Business And Organization [Line Items]
Business Acquisition, Transaction Costs	$ 305.2			$ 1,100.0
Rent payments due under master lease	$ 60.0
Exchange of Operating Partnership Units to MGP's Class A Shares
Business And Organization [Line Items]
Operating Partnership unit conversion ratio					1
MGM
Business And Organization [Line Items]
Operating Partnership units held (in shares)					199.7
Increase in ownership interest in operating partnership ( as a percent )					68.30%
MGP Operating Partnership
Business And Organization [Line Items]
Operating Partnership units outstanding (in shares)					292,341,429				266,045,289