Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
	Sep. 23, 2015	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Commitments and Contingencies [Line Items]
Total operating lease expense			$ 24.1	$ 25.3	$ 26.6
Loss Contingency, name of plaintiff		Baldwin Hackett & Meeks, Inc.
Loss contingency, damages sought, value	$ 43.8
Loss contingency, damages awarded, value		$ 43.8
BHMI judgment and related fees and interest expense		$ 2.7	48.1
General and Administrative Expense [Member]
Commitments and Contingencies [Line Items]
BHMI judgment and related fees and interest expense			46.7
Interest Expense [Member]
Commitments and Contingencies [Line Items]
BHMI judgment and related fees and interest expense			$ 1.4