Equity Investments - Equity Losses and Dividends Received (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Equity Method Investments And Joint Ventures [Abstract]
Equity loss	$ (1.0)	$ (2.2)	$ (1.6)