Intangible Assets, Net - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended			9 Months Ended		3 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Sep. 30, 2014 Customer Relationships [Member]	Dec. 31, 2013 Customer Relationships [Member]	Jun. 30, 2014 PDRI [Member] Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated fair value of asset								$ 7,900,000
Carrying value	279,607,000		279,607,000		309,692,000	145,998,000	167,077,000	28,700,000
Pre-tax impairment loss			20,800,000			20,800,000		20,800,000
Amortization expense	$ 9,700,000	$ 8,700,000	$ 29,500,000	$ 26,100,000