Earnings Per Share - Calculation of Earnings Per Share (Detail) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income	$ 736,476	$ 76,881	$ 939,536	$ 218,862
Net income attributable to non-controlling interests	(442)	(417)	(1,334)	(1,013)
Participating securities’ share in earnings	(290)	(82)	(808)	(307)
Net income, less participating securities’ share in earnings	$ 735,744	$ 76,382	$ 937,394	$ 217,542
Basic weighted-average common shares	365,024	364,315	364,934	345,076
Dilutive potential common shares	1,443	731	850	520
Dilutive weighted-average common shares	366,467	365,046	365,784	345,596
MPT Operating Partnership, L.P. [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income	$ 736,476	$ 76,881	$ 939,536	$ 218,862
Net income attributable to non-controlling interests	(442)	(417)	(1,334)	(1,013)
Participating securities’ share in earnings	(290)	(82)	(808)	(307)
Net income, less participating securities’ share in earnings	$ 735,744	$ 76,382	$ 937,394	$ 217,542
Basic weighted-average common shares	365,024	364,315	364,934	345,076
Dilutive potential common shares	1,443	731	850	520
Dilutive weighted-average common shares	366,467	365,046	365,784	345,596