Basis of Presentation - Merger - Additional Information (Detail) $ in Thousands		Sep. 16, 2016 USD ($) shares	Sep. 30, 2016 USD ($)
Business Acquisition Equity Interests Issued Or Issuable [Line Items]
Goodwill			$ 1,630,981
Memorial
Business Acquisition Equity Interests Issued Or Issuable [Line Items]
Common stock issued in connection with exchange of outstanding shares | shares		77,042,749
Exchange ratio of common shares for acquired company		0.375
Goodwill	[1]	$ 1,630,981

[1] Goodwill will not be deductible for income tax purposes.