Intangible Assets, Net - Summary of Carrying Amount of Intangible Assets by Major Asset Class (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 301,230	$ 294,347
Accumulated Amortization	(63,528)	(40,084)
Net Carrying Value	237,702	254,263	$ 280,217
Customer Relationship [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	282,030	275,130
Accumulated Amortization	(52,408)	(30,137)
Net Carrying Value	229,622	244,993
Other Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	19,200	19,217
Accumulated Amortization	(11,120)	(9,947)
Net Carrying Value	$ 8,080	$ 9,270
Minimum [Member] | Customer Relationship [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life in Years	12 years
Minimum [Member] | Other Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life in Years	1 year
Maximum [Member] | Customer Relationship [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life in Years	15 years
Maximum [Member] | Other Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life in Years	15 years