Description of Business and Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Accounting Policies [Abstract]
Settlement of fund for eligible participants		$ (12.3)
Reimbursement of workers compensation insurance claims included in other current assets	$ 21.1	$ 25.1
Future net cash flow discount rate	10.00%