Goodwill and Other Intangibles - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Goodwill and Intangible Assets Disclosure [Line Items]
Estimated future amortization expense for 2015	$ 4.2		$ 4.2
Estimated future amortization expense for 2016	8.5		8.5
Estimated future amortization expense for 2017	8.4		8.4
Estimated future amortization expense for 2018	7.8		7.8
Estimated future amortization expense for 2019	7.6		7.6
Other Intangible Assets
Goodwill and Intangible Assets Disclosure [Line Items]
Amortization expense related to other intangible assets	$ 2.1	$ 5.0	$ 6.7	$ 9.9