Premises and Equipment, Net - Schedule of Premises and Equipment, Net (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Premises and equipment	$ 305,014	$ 289,740
Less: accumulated depreciation and amortization	(222,386)	(183,259)
Premises and equipment, net	82,628	106,481
Computer Software [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment	$ 239,868	213,923
Computer Software [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Useful Life	3 years
Computer Software [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Useful Life	7 years
Computer Hardware [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment	$ 36,515	35,120
Useful Life	3 years
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment	$ 10,543	10,649
Useful Life	3 years
Office Equipment and Other [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment	$ 13,347	6,053
Useful Life	3 years
Assets in development [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment	$ 4,741	$ 23,995