Condensed Consolidating Financial Information - Consolidating Statement of Operations and Comprehensive Income Information (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Condensed Income Statements, Captions [Line Items]
Revenues	$ 225,759		$ 220,390		$ 429,182	$ 436,229
Expenses
Depreciation	79,543		67,474		151,105	136,465
Property transactions, net	310		14,426		1,423	18,512
Ground lease and other reimbursable expenses	5,920		32,907		11,840	61,267
Amortization of above market lease, net	0		172		0	343
Acquisition-related expenses	267		2,131		8,799	2,672
General and administrative	3,691		2,755		7,829	6,663
Expenses, net	89,731		119,865		180,996	225,922
Operating income	136,028		100,525		248,186	210,307
Other income (expense)
Interest income	102		1,278		1,948	2,310
Interest expense	(63,977)		(49,276)		(127,925)	(98,506)
Other	(363)		(3,205)		(500)	(5,389)
Non-operating income (expense)	(64,238)		(51,203)		(126,477)	(101,585)
Income from continuing operations before income taxes	71,790		49,322		121,709	108,722
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	24,783		39,519		60,297	93,855
Income from continuing operations attributable to noncontrolling interest	45,911		34,913		80,886	77,252
Provision for income taxes	(4,021)		(1,263)		(3,792)	(2,494)
Income from discontinued operations attributable to noncontrolling interest	0		0		11,434	0
Net income	67,769	$ 66,364	48,059	$ 58,169	134,133	106,228
Other comprehensive income (loss)
Unrealized gain (loss) on cash flow hedges, net	(30,775)		6,281		(46,387)	22,636
Comprehensive income	36,994		54,340		87,746	128,864
Rental revenue
Condensed Income Statements, Captions [Line Items]
Revenues	219,846		186,563		416,728	373,126
Tenant reimbursements and other
Condensed Income Statements, Captions [Line Items]
Revenues	5,913		33,827		12,454	63,103
MGP Operating Partnership
Condensed Income Statements, Captions [Line Items]
Revenues	225,759		220,390		429,182	436,229
Expenses
Depreciation	79,543		67,474		151,105	136,465
Property transactions, net	310		14,426		1,423	18,512
Ground lease and other reimbursable expenses	5,920		32,907		11,840	61,267
Amortization of above market lease, net	0		172		0	343
Acquisition-related expenses	267		2,131		8,799	2,672
General and administrative	3,691		2,755		7,829	6,663
Expenses, net	89,731		119,865		180,996	225,922
Operating income	136,028		100,525		248,186	210,307
Equity in earnings of subsidiaries	0		0		0	0
Other income (expense)
Interest income	102		1,278		1,948	2,310
Interest expense	(63,977)		(49,276)		(127,925)	(98,506)
Other	(363)		(3,205)		(500)	(5,389)
Non-operating income (expense)	(64,238)		(51,203)		(126,477)	(101,585)
Income from continuing operations before income taxes	71,790		49,322		121,709	108,722
Provision for income taxes	(4,021)		(1,263)		(3,792)	(2,494)
Net income	67,769	$ 66,364	48,059	$ 58,169	134,133	106,228
Other comprehensive income (loss)
Unrealized gain (loss) on cash flow hedges, net	(30,775)		6,281		(46,387)	22,636
Comprehensive income	36,994		54,340		87,746	128,864
MGP Operating Partnership | Rental revenue
Condensed Income Statements, Captions [Line Items]
Revenues	219,846		186,563		416,728	373,126
Other income (expense)
Income from continuing operations attributable to noncontrolling interest	67,769				117,917
Income from discontinued operations attributable to noncontrolling interest					16,216
MGP Operating Partnership | Tenant reimbursements and other
Condensed Income Statements, Captions [Line Items]
Revenues	5,913		33,827		12,454	63,103
MGP Operating Partnership | Eliminations
Condensed Income Statements, Captions [Line Items]
Revenues	0		0		0	0
Expenses
Depreciation	0		0		0	0
Property transactions, net	0		0		0	0
Ground lease and other reimbursable expenses	0		0		0	0
Amortization of above market lease, net			0			0
Acquisition-related expenses	0		0		0	0
General and administrative	0		0		0	0
Expenses, net	0		0		0	0
Operating income	0		0		0	0
Equity in earnings of subsidiaries	(137,732)		(104,163)		(273,409)	(217,190)
Other income (expense)
Interest income	0		0		(5,617)	0
Interest expense	0		0		5,617	0
Other	0		0		0	0
Non-operating income (expense)	0		0		0	0
Income from continuing operations before income taxes	(137,732)		(104,163)		(273,409)	(217,190)
Provision for income taxes	0		0		0	0
Net income	(137,732)		(104,163)		(273,409)	(217,190)
Other comprehensive income (loss)
Unrealized gain (loss) on cash flow hedges, net	0		0		0	0
Comprehensive income	(137,732)		(104,163)		(273,409)	(217,190)
MGP Operating Partnership | Eliminations | Rental revenue
Condensed Income Statements, Captions [Line Items]
Revenues	0		0		0	0
Other income (expense)
Income from continuing operations attributable to noncontrolling interest	(137,732)				(273,409)
Income from discontinued operations attributable to noncontrolling interest					0
MGP Operating Partnership | Eliminations | Tenant reimbursements and other
Condensed Income Statements, Captions [Line Items]
Revenues	0		0		0	0
MGP Operating Partnership | Operating Partnership | Reportable Legal Entities
Condensed Income Statements, Captions [Line Items]
Revenues	0		0		0	0
Expenses
Depreciation	22		15		43	42
Property transactions, net	0		0		0	0
Ground lease and other reimbursable expenses	0		0		0	0
Amortization of above market lease, net			0			0
Acquisition-related expenses	267		2,131		8,799	2,672
General and administrative	3,691		2,755		7,829	6,663
Expenses, net	3,980		4,901		16,671	9,377
Operating income	(3,980)		(4,901)		(16,671)	(9,377)
Equity in earnings of subsidiaries	137,732		104,163		273,409	217,190
Other income (expense)
Interest income	102		1,278		7,565	2,310
Interest expense	(63,977)		(49,276)		(127,925)	(98,506)
Other	(363)		(3,205)		(500)	(5,389)
Non-operating income (expense)	(64,238)		(51,203)		(120,860)	(101,585)
Income from continuing operations before income taxes	69,514		48,059		135,878	106,228
Provision for income taxes	(1,745)		0		(1,745)	0
Net income	67,769		48,059		134,133	106,228
Other comprehensive income (loss)
Unrealized gain (loss) on cash flow hedges, net	(30,775)		6,281		(46,387)	22,636
Comprehensive income	36,994		54,340		87,746	128,864
MGP Operating Partnership | Operating Partnership | Reportable Legal Entities | Rental revenue
Condensed Income Statements, Captions [Line Items]
Revenues	0		0		0	0
Other income (expense)
Income from continuing operations attributable to noncontrolling interest	67,769				134,133
Income from discontinued operations attributable to noncontrolling interest					0
MGP Operating Partnership | Operating Partnership | Reportable Legal Entities | Tenant reimbursements and other
Condensed Income Statements, Captions [Line Items]
Revenues	0		0		0	0
MGP Operating Partnership | Co-Issuer | Reportable Legal Entities
Condensed Income Statements, Captions [Line Items]
Revenues	0		0		0	0
Expenses
Depreciation	0		0		0	0
Property transactions, net	0		0		0	0
Ground lease and other reimbursable expenses	0		0		0	0
Amortization of above market lease, net			0			0
Acquisition-related expenses	0		0		0	0
General and administrative	0		0		0	0
Expenses, net	0		0		0	0
Operating income	0		0		0	0
Equity in earnings of subsidiaries	0		0		0	0
Other income (expense)
Interest income	0		0		0	0
Interest expense	0		0		0	0
Other	0		0		0	0
Non-operating income (expense)	0		0		0	0
Income from continuing operations before income taxes	0		0		0	0
Provision for income taxes	0		0		0	0
Net income	0		0		0	0
Other comprehensive income (loss)
Unrealized gain (loss) on cash flow hedges, net	0		0		0	0
Comprehensive income	0		0		0	0
MGP Operating Partnership | Co-Issuer | Reportable Legal Entities | Rental revenue
Condensed Income Statements, Captions [Line Items]
Revenues	0		0		0	0
Other income (expense)
Income from continuing operations attributable to noncontrolling interest	0				0
Income from discontinued operations attributable to noncontrolling interest					0
MGP Operating Partnership | Co-Issuer | Reportable Legal Entities | Tenant reimbursements and other
Condensed Income Statements, Captions [Line Items]
Revenues	0		0		0	0
MGP Operating Partnership | Guarantor Subsidiaries | Reportable Legal Entities
Condensed Income Statements, Captions [Line Items]
Revenues	225,759		220,390		429,182	436,229
Expenses
Depreciation	79,521		67,459		151,062	136,423
Property transactions, net	310		14,426		1,423	18,512
Ground lease and other reimbursable expenses	5,920		32,907		11,840	61,267
Amortization of above market lease, net			172			343
Acquisition-related expenses	0		0		0	0
General and administrative	0		0		0	0
Expenses, net	85,751		114,964		164,325	216,545
Operating income	140,008		105,426		264,857	219,684
Equity in earnings of subsidiaries	0		0		0	0
Other income (expense)
Interest income	0		0		0	0
Interest expense	0		0		(5,617)	0
Other	0		0		0	0
Non-operating income (expense)	0		0		(5,617)	0
Income from continuing operations before income taxes	140,008		105,426		259,240	219,684
Provision for income taxes	(2,276)		(1,263)		(2,047)	(2,494)
Net income	137,732		104,163		273,409	217,190
Other comprehensive income (loss)
Unrealized gain (loss) on cash flow hedges, net	0		0		0	0
Comprehensive income	137,732		104,163		273,409	217,190
MGP Operating Partnership | Guarantor Subsidiaries | Reportable Legal Entities | Rental revenue
Condensed Income Statements, Captions [Line Items]
Revenues	219,846		186,563		416,728	373,126
Other income (expense)
Income from continuing operations attributable to noncontrolling interest	137,732				257,193
Income from discontinued operations attributable to noncontrolling interest					16,216
MGP Operating Partnership | Guarantor Subsidiaries | Reportable Legal Entities | Tenant reimbursements and other
Condensed Income Statements, Captions [Line Items]
Revenues	$ 5,913		$ 33,827		$ 12,454	$ 63,103