Basis of Presentation and Significant Accounting Policies (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jan. 01, 2017
Accounting Policies [Abstract]
Effective income tax rate, continuing operations	20.50%	61.70%
Restatement adjustment [Member] | Accounting Standards Update 2016-18 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase in restricted cash		$ 466.3
Retained earnings [Member] | New accounting pronouncement, early adoption, effect [Member] | Accounting Standards Update 2016-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment			$ 1.1