Goodwill and Intangible Assets - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Schedule Of Goodwill And Other Intangible Assets [Line Items]
Amortization expense of finite life intangible assets	$ 3,300,000	$ 1,700,000	$ 8,513,000	$ 5,342,000
Amortization expense of finite life intangibles for 2015	4,700,000		4,700,000
Amortization expense of finite life intangibles for 2016	16,900,000		16,900,000
Amortization expense of finite life intangibles for 2017	13,000,000		13,000,000
Amortization expense of finite life intangibles for 2018	10,700,000		10,700,000
Amortization expense of finite life intangibles for 2019	8,900,000		8,900,000
Goodwill	232,240,000		232,240,000		$ 167,547,000	$ 134,062,000
Indefinite-lived intangible assets	30,249,000		30,249,000		19,766,000	18,419,000
Definite-lived intangible assets	83,975,000	$ 40,399,000	83,975,000	$ 40,399,000	58,398,000	$ 46,611,000
Reporting Unit One [Member]
Schedule Of Goodwill And Other Intangible Assets [Line Items]
Goodwill	77,900,000		$ 77,900,000
Goodwill impairment charges					0
Decrease in projected revenue growth rate			0.30%
Decrease in projected operational profit			0.70%
Indefinite-lived intangible assets	6,800,000		$ 6,800,000
Reporting Unit One [Member] | Indefinite-lived Intangible Assets [Member]
Schedule Of Goodwill And Other Intangible Assets [Line Items]
Decrease in projected revenue growth rate			0.70%
Reporting Unit Two [Member]
Schedule Of Goodwill And Other Intangible Assets [Line Items]
Goodwill	13,000,000		$ 13,000,000		$ 90,900,000
Estimated fair value of goodwill exceeds from its carrying value					3.00%
Decrease in projected revenue growth rate			1.00%
Decrease in projected operational profit			0.90%
Indefinite-lived intangible assets	2,300,000		$ 2,300,000
Indefinite life intangible assets, impairment charges					$ 0
Definite-lived intangible assets					$ 24,000,000
Reporting Unit Two [Member] | Indefinite-lived Intangible Assets [Member]
Schedule Of Goodwill And Other Intangible Assets [Line Items]
Decrease in projected revenue growth rate			0.40%
Three Reporting Units [Member]
Schedule Of Goodwill And Other Intangible Assets [Line Items]
Estimated fair value of goodwill exceeds from its carrying value					5.00%
Indefinite-lived intangible assets	$ 900,000		$ 900,000		$ 10,000,000
Three Reporting Units [Member] | Indefinite-lived Intangible Assets [Member]
Schedule Of Goodwill And Other Intangible Assets [Line Items]
Decrease in projected revenue growth rate			1.60%
Four Reporting Units [Member]
Schedule Of Goodwill And Other Intangible Assets [Line Items]
Goodwill					105,400,000
Five Reporting Units [Member]
Schedule Of Goodwill And Other Intangible Assets [Line Items]
Indefinite-lived intangible assets					$ 13,500,000