Effects of Restatement on Condensed Consolidated Statements of Cash Flows (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash provided (required) by operating activities:
Net income	$ (15.2)	$ 120.6
Amortization	68.0	5.2
Deferred income tax provision (benefit)	4.0	(19.8)
Other	54.0	(2.1)
Advance payments and billings in excess of costs	43.3	(83.4)
Previously Reported
Cash provided (required) by operating activities:
Net income	194.3	147.3
Amortization	70.9
Deferred income tax provision (benefit)	55.9	(18.2)
Other	53.6	(22.2)
Advance payments and billings in excess of costs	(220.6)	(91.6)
Restatement Adjustment
Cash provided (required) by operating activities:
Net income	(209.5)	(26.7)
Amortization	(2.9)
Deferred income tax provision (benefit)	(51.9)	(1.6)
Other	0.4	20.1
Advance payments and billings in excess of costs	$ 263.9	$ 8.2