Minimum Regulatory Capital Requirements - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Common equity tier 1 capital conservation buffer period	3 years
Common equity tier 1 capital conservation buffer with initial phase (as a percent)	0.625%
Minimum [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Capital conservation buffer of common equity tier 1 capital to risk weighted assets ratio (as a percent)	2.50%