Professional Fees and Other Expenses - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Selling, General and Administrative Expenses [Member]
Professional Fees And Other Expenses [Line Items]
Professional fees and other expenses	$ 12.1	$ 18.7	$ 25.1