Dispositions and Acquisitions - Acquisitions - Additional Information (Detail) $ in Thousands		3 Months Ended				4 Months Ended	12 Months Ended
	Sep. 16, 2016 USD ($) shares	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Business Acquisition [Line Items]
Merger-related expenses		$ 813	$ 33,791	$ 2,621	$ 0		$ 37,225	$ 0	$ 0
MRD
Business Acquisition [Line Items]
Business merger date							Sep. 16, 2016
Common stock issued in connection with exchange of outstanding shares | shares	77,042,749
Exchange ratio of common shares for acquired company	0.375
Fair value of outstanding debt	$ 1,204,449
Merger-related expenses	$ 37,225
Revenues						$ 146,600
Net operating income						$ 94,900
Merger related costs incurred by Memorial excluded from ProForma							$ 7,100