Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Contingencies And Commitments [Line Items]
Rent expense	$ 6.1	$ 4.4	$ 10.3	$ 8.8
Minimum [Member]
Contingencies And Commitments [Line Items]
Lease term			1 year
Maximum [Member]
Contingencies And Commitments [Line Items]
Lease term			20 years