Commitments and Contingencies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Loss Contingencies [Line Items]
Credit arrangements	$ 35,000,000
Contingent liability	8,000,000
Rental expense	50,000,000	$ 50,000,000	$ 51,000,000
Total future lease commitments	109,000,000
Series of Individually Immaterial Business Acquisitions [Member]
Loss Contingencies [Line Items]
Rental expense	3,000,000	$ 3,000,000
Total future lease commitments	$ 9,000,000
Operating leases, expiry year	2023
Minimum [Member]
Loss Contingencies [Line Items]
Range of reasonably possible losses	$ 0
Maximum [Member]
Loss Contingencies [Line Items]
Range of reasonably possible losses	$ 15,000,000