Acquisitions and Dispositions - Acquisitions - Additional Information (Detail) $ in Thousands		1 Months Ended	3 Months Ended		9 Months Ended
	Sep. 16, 2016 USD ($) shares	Sep. 30, 2016 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)
Business Acquisition [Line Items]
Merger-related costs			$ 33,791	$ 0	$ 36,412	$ 0
Memorial
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 costs	$ 36,412
Revenues		$ 21,100
Net operating income		$ 12,300
Merger related costs incurred by Memorial excluded from ProForma			$ 9,300		$ 9,300