Shareholders' Equity and Partners' Capital - Distributions and Dividends Declared and Paid (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended
	Apr. 15, 2018	Apr. 13, 2017	Mar. 31, 2018
Class of Stock [Line Items]
MGP Class A Dividend			$ 111,733
Class A Shares
Class of Stock [Line Items]
Dividend Per Share (in dollars per share)		$ 387.5000
MGP Class A Dividend		$ 22,281
MGP Operating Partnership
Class of Stock [Line Items]
Distribution Per Unit (in dollars per share)		$ 387.5000
Operating Partnership Distribution		$ 94,109
Subsequent Event | Class A Shares
Class of Stock [Line Items]
Dividend Per Share (in dollars per share)	$ 420.00
MGP Class A Dividend	$ 29,777
Subsequent Event | MGP Operating Partnership
Class of Stock [Line Items]
Distribution Per Unit (in dollars per share)	$ 420.00
Operating Partnership Distribution	$ 111,733