Net Income (Loss) Per Common Share - Basic Weighted Average Common Shares Outstanding to Diluted Weighted Average Common Shares Outstanding (Detail) - shares shares in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Denominator:
Weighted average common shares outstanding – basic	[1]	245,091	189,868	166,389
Effect of dilutive securities:
Director and employee restricted stock and performance-based equity awards		367	0	0
Weighted average common shares outstanding – diluted		245,458	189,868	166,389

[1] Includes common stock issued in connection with the exchange of 77.0 million shares for all outstanding Memorial common stock on September 16, 2016.