Goodwill and Other Intangibles - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Goodwill and Intangible Assets Disclosure [Line Items]
Estimated future amortization expense for 2015	$ 11.3
Estimated future amortization expense for 2016	8.8
Estimated future amortization expense for 2017	8.7
Estimated future amortization expense for 2018	8.1
Estimated future amortization expense for 2019	7.9
Other Intangible Assets
Goodwill and Intangible Assets Disclosure [Line Items]
Amortization expense related to other intangible assets	$ 19.5	$ 21.1	$ 20.3