Condensed Consolidating Financial Information - Schedule of Condensed Consolidating Statement of Cash Flows Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities
Net cash provided by (used in) operating activities	$ 577,664	$ 405,435
Cash flows from investing activities
Capital expenditures, net of construction payable	(418,624)	(456,075)
Dispositions of property and equipment	225	180
Investments in unconsolidated affiliates	(2,503)	(3,500)
Intercompany accounts	0	0
Other	(11,475)	(6,554)
Net cash used in investing activities	(432,377)	(465,949)
Cash flows from financing activities
Net borrowings under bank credit facilities – maturities of 90 days or less	380,035	107,480
Debt issuance costs	(4,544)	(4,905)
Dividends paid to common shareholders	(67,999)	(63,182)
Distributions to noncontrolling interest owners	(47,380)	(24,843)
MGP Operating Partnership distributions paid to consolidated subsidiaries	0	0
Purchases of common stock	(362,400)	0
Retirement of debentures	(2,265)	0
Intercompany accounts	0	0
Other	(12,497)	(4,084)
Net cash provided by (used in) financing activities	(117,050)	10,466
Effect of exchange rate on cash	(2,830)	(1,089)
Cash and cash equivalents
Net increase (decrease) for the period	25,407	(51,137)
Balance, beginning of period	1,499,995	1,446,581
Balance, end of period	1,525,402	1,395,444
Reportable Legal Entities [Member] | Parent [Member]
Cash flows from operating activities
Net cash provided by (used in) operating activities	(157,092)	(172,712)
Cash flows from investing activities
Capital expenditures, net of construction payable	0	0
Dispositions of property and equipment	0	0
Investments in unconsolidated affiliates	0	0
Intercompany accounts	0	0
Other	0	0
Net cash used in investing activities	0	0
Cash flows from financing activities
Net borrowings under bank credit facilities – maturities of 90 days or less	516,875	46,875
Debt issuance costs	0	0
Dividends paid to common shareholders	(67,999)	(63,182)
Distributions to noncontrolling interest owners	0	0
MGP Operating Partnership distributions paid to consolidated subsidiaries	0	0
Purchases of common stock	(362,400)
Retirement of debentures	0
Intercompany accounts	111,580	165,879
Other	(8,297)	(4,077)
Net cash provided by (used in) financing activities	189,759	145,495
Effect of exchange rate on cash	0	0
Cash and cash equivalents
Net increase (decrease) for the period	32,667	(27,217)
Balance, beginning of period	26,870	99,995
Balance, end of period	59,537	72,778
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Cash flows from operating activities
Net cash provided by (used in) operating activities	237,173	228,839
Cash flows from investing activities
Capital expenditures, net of construction payable	(181,743)	(79,464)
Dispositions of property and equipment	220	89
Investments in unconsolidated affiliates	(2,503)	(3,500)
Intercompany accounts	(102,195)	(222,118)
Other	(9,937)	(3,710)
Net cash used in investing activities	(296,158)	(308,703)
Cash flows from financing activities
Net borrowings under bank credit facilities – maturities of 90 days or less	0	0
Debt issuance costs	0	0
Dividends paid to common shareholders	0	0
Distributions to noncontrolling interest owners	0	0
MGP Operating Partnership distributions paid to consolidated subsidiaries	0	0
Purchases of common stock	0
Retirement of debentures	(2,265)
Intercompany accounts	26,042	59,309
Other	(2,793)	0
Net cash provided by (used in) financing activities	20,984	59,309
Effect of exchange rate on cash	0	0
Cash and cash equivalents
Net increase (decrease) for the period	(38,001)	(20,555)
Balance, beginning of period	311,043	307,713
Balance, end of period	273,042	287,158
Reportable Legal Entities [Member] | Non-Guarantor MGP Subsidiaries [Member]
Cash flows from operating activities
Net cash provided by (used in) operating activities	145,224	119,191
Cash flows from investing activities
Capital expenditures, net of construction payable	(177)	0
Dispositions of property and equipment	0	0
Investments in unconsolidated affiliates	0	0
Intercompany accounts	0	0
Other	0	0
Net cash used in investing activities	(177)	0
Cash flows from financing activities
Net borrowings under bank credit facilities – maturities of 90 days or less	(8,375)	(16,750)
Debt issuance costs	(4,544)	(526)
Dividends paid to common shareholders	0	0
Distributions to noncontrolling interest owners	(29,777)	(22,282)
MGP Operating Partnership distributions paid to consolidated subsidiaries	(81,956)	(71,827)
Purchases of common stock	0
Retirement of debentures	0
Intercompany accounts	0	0
Other	0	0
Net cash provided by (used in) financing activities	(124,652)	(111,385)
Effect of exchange rate on cash	0	0
Cash and cash equivalents
Net increase (decrease) for the period	20,395	7,806
Balance, beginning of period	259,722	360,492
Balance, end of period	280,117	368,298
Reportable Legal Entities [Member] | Non-Guarantor Other Subsidiaries [Member]
Cash flows from operating activities
Net cash provided by (used in) operating activities	352,359	230,117
Cash flows from investing activities
Capital expenditures, net of construction payable	(236,704)	(376,611)
Dispositions of property and equipment	5	91
Investments in unconsolidated affiliates	0	0
Intercompany accounts	0	0
Other	(1,538)	(2,844)
Net cash used in investing activities	(238,237)	(379,364)
Cash flows from financing activities
Net borrowings under bank credit facilities – maturities of 90 days or less	(128,465)	77,355
Debt issuance costs	0	(4,379)
Dividends paid to common shareholders	0	0
Distributions to noncontrolling interest owners	(17,603)	(2,561)
MGP Operating Partnership distributions paid to consolidated subsidiaries	0	0
Purchases of common stock	0
Retirement of debentures	0
Intercompany accounts	46,529	68,757
Other	(1,407)	(7)
Net cash provided by (used in) financing activities	(100,946)	139,165
Effect of exchange rate on cash	(2,830)	(1,089)
Cash and cash equivalents
Net increase (decrease) for the period	10,346	(11,171)
Balance, beginning of period	902,360	678,381
Balance, end of period	912,706	667,210
Elimination [Member]
Cash flows from operating activities
Net cash provided by (used in) operating activities	0	0
Cash flows from investing activities
Capital expenditures, net of construction payable	0	0
Dispositions of property and equipment	0	0
Investments in unconsolidated affiliates	0	0
Intercompany accounts	102,195	222,118
Other	0	0
Net cash used in investing activities	102,195	222,118
Cash flows from financing activities
Net borrowings under bank credit facilities – maturities of 90 days or less	0	0
Debt issuance costs	0	0
Dividends paid to common shareholders	0	0
Distributions to noncontrolling interest owners	0	0
MGP Operating Partnership distributions paid to consolidated subsidiaries	81,956	71,827
Purchases of common stock	0
Retirement of debentures	0
Intercompany accounts	(184,151)	(293,945)
Other	0	0
Net cash provided by (used in) financing activities	(102,195)	(222,118)
Effect of exchange rate on cash	0	0
Cash and cash equivalents
Net increase (decrease) for the period	0	0
Balance, beginning of period	0	0
Balance, end of period	$ 0	$ 0