Shareholders' Equity and Partners' Capital - Distributions and Dividends Declared and Paid (Details) - USD ($) $ / shares in Units, $ in Thousands					6 Months Ended
	Jul. 16, 2018	Apr. 15, 2018	Jul. 14, 2017	Apr. 13, 2017	Jun. 30, 2018
Class of Stock [Line Items]
MGP Class A Dividend					$ 226,133
Class A Shares
Class of Stock [Line Items]
Dividend Per Share (in dollars per share)		$ 420.00	$ 395.000	$ 387.5000
MGP Class A Dividend		$ 29,777	$ 22,777	$ 22,281
Class A Shares | Subsequent Event
Class of Stock [Line Items]
Dividend Per Share (in dollars per share)	$ 430.00
MGP Class A Dividend	$ 30,492
MGP Operating Partnership
Class of Stock [Line Items]
Distribution Per Unit (in dollars per share)		$ 420.00	$ 395.0000	$ 387.5000
Operating Partnership Distribution		$ 111,733	$ 95,995	$ 94,109
MGP Operating Partnership | Subsequent Event
Class of Stock [Line Items]
Distribution Per Unit (in dollars per share)	$ 430.00
Operating Partnership Distribution	$ 114,399