Basis of Presentation - Correction of Prior Period Balances (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Noninterest income - Other revenue	$ 5,196	$ 4,570
Noninterest expense - Other operating expense	$ 9,119	7,659
Immaterial error, cash servicing fees
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Noninterest income - Other revenue		4,570
Noninterest expense - Other operating expense		7,659
Immaterial error, cash servicing fees | As originally reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Noninterest income - Other revenue		3,972
Noninterest expense - Other operating expense		7,061
Immaterial error, cash servicing fees | Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Noninterest income - Other revenue		598
Noninterest expense - Other operating expense		$ 598