Earnings Per Share/Unit - Calculation of Earnings Per Share (Detail) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income	$ 78,941	$ 736,476	$ 112,017	$ 91,043	$ 72,376	$ 76,881	$ 73,796	$ 68,185	$ 1,018,477	$ 291,238	$ 225,937
Net income attributable to non-controlling interests									(1,792)	(1,445)	(889)
Participating securities’ share in earnings									(3,685)	(1,409)	(559)
Net income, less participating securities’ share in earnings									$ 1,013,000	$ 288,384	$ 224,489
Weighted average shares outstanding — basic	366,655	365,024	364,897	364,882	364,382	364,315	349,856	321,057	365,364	349,902	260,414
Dilutive potential common shares									907	539	658
Diluted weighted average common shares	367,732	366,467	365,541	365,343	364,977	365,046	350,319	321,423	366,271	350,441	261,072
MPT Operating Partnership, L.P. [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income	$ 78,941	$ 736,476	$ 112,017	$ 91,043	$ 72,376	$ 76,881	$ 73,796	$ 68,185	$ 1,018,477	$ 291,238	$ 225,937
Net income attributable to non-controlling interests									(1,792)	(1,445)	(889)
Participating securities’ share in earnings									(3,685)	(1,409)	(559)
Net income, less participating securities’ share in earnings									$ 1,013,000	$ 288,384	$ 224,489
Weighted average shares outstanding — basic	366,655	365,024	364,897	364,882	364,382	364,315	349,856	321,057	365,364	349,902	260,414
Dilutive potential common shares									907	539	658
Diluted weighted average common shares	367,732	366,467	365,541	365,343	364,977	365,046	350,319	321,423	366,271	350,441	261,072