Goodwill and Intangible Assets - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule Of Goodwill And Other Intangible Assets [Line Items]
Aggregate amount of goodwill acquired	$ 237,300,000
Aggregate amount of impairment	17,100,000
Goodwill	220,163,000	$ 165,861,000	$ 129,888,000
Intangible assets – indefinite life	26,337,000	19,766,000	18,419,000
Impairment of intangible assets	3,340,000
Goodwill or indefinite life intangible asset charges		0	0
Amortization expense of finite life intangible assets	12,300,000	$ 7,600,000	$ 4,700,000
Amortization expense of finite life intangibles for 2016	14,000,000
Amortization expense of finite life intangibles for 2017	11,600,000
Amortization expense of finite life intangibles for 2018	10,000,000
Amortization expense of finite life intangibles for 2019	8,900,000
Amortization expense of finite life intangibles for 2020	7,100,000
Reporting Unit One [Member]
Schedule Of Goodwill And Other Intangible Assets [Line Items]
Goodwill impairment charges	0
Goodwill	$ 77,900,000
Estimated fair value of goodwill exceeds from its carrying value	8.00%
Decrease in projected revenue growth rate	1.10%
Decrease in projected operational profit	3.90%
Three Reporting Units [Member]
Schedule Of Goodwill And Other Intangible Assets [Line Items]
Intangible assets – indefinite life	$ 10,000,000
Fair value lower than the aggregate carrying value	33.40%
Impairment of intangible assets	$ 3,300,000