Earnings Per Share/Unit - Calculation of Earnings Per Share (Detail) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income	$ 76,291	$ 91,043
Net income attributable to non-controlling interests	(469)	(442)
Participating securities’ share in earnings	(476)	(195)
Net income, less participating securities’ share in earnings	$ 75,346	$ 90,406
Basic weighted-average common shares	380,551	364,882
Dilutive potential common shares	1,124	461
Dilutive weighted-average common shares	381,675	365,343
MPT Operating Partnership, L.P. [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income	$ 76,291	$ 91,043
Net income attributable to non-controlling interests	(469)	(442)
Participating securities’ share in earnings	(476)	(195)
Net income, less participating securities’ share in earnings	$ 75,346	$ 90,406
Basic weighted-average common shares	380,551	364,882
Dilutive potential common shares	1,124	461
Dilutive weighted-average common shares	381,675	365,343