Goodwill and Intangible Assets, Net - Schedule of Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Feb. 09, 2018	Dec. 31, 2017
Finite-lived Intangible Assets [Roll Forward]
Gross Carrying Amount	$ 44,650		$ 51,041
Accumulated Amortization	(14,181)		(35,573)
Accumulated Impairment	(14,700)		(6,735)
Net Carrying Amount	15,769		8,733
Institutional and Customer Relationships [Member]
Finite-lived Intangible Assets [Roll Forward]
Gross Carrying Amount	24,000		41,041
Accumulated Amortization	(13,640)		(30,793)
Accumulated Impairment	0		(6,340)
Net Carrying Amount	10,360		3,908
Trademarks and Trade Names [Member]
Finite-lived Intangible Assets [Roll Forward]
Gross Carrying Amount	20,000		10,000
Accumulated Amortization			(4,780)
Accumulated Impairment	(14,700)		(395)
Net Carrying Amount	5,300		4,825
Other Intangible Assets [Member]
Finite-lived Intangible Assets [Roll Forward]
Gross Carrying Amount	650		0
Accumulated Amortization	(541)		0
Accumulated Impairment	0		0
Net Carrying Amount	$ 109		$ 0
Fresh-Start Adjustments [Member]
Finite-lived Intangible Assets [Roll Forward]
Increase to intangible assets		$ 35,468
Fresh-Start Adjustments [Member] | Institutional and Customer Relationships [Member]
Finite-lived Intangible Assets [Roll Forward]
Increase to intangible assets		20,200
Fresh-Start Adjustments [Member] | Trademarks and Trade Names [Member]
Finite-lived Intangible Assets [Roll Forward]
Increase to intangible assets		$ 15,200