Regulatory Matters - Additional Information (Detail) - USD ($)	1 Months Ended	6 Months Ended
	Jan. 31, 2016	Jun. 30, 2016	Dec. 31, 2014
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common equity tier one capital ratio		4.50%
Tier 1 risk based capital ratios	8.50%	6.00%	4.00%
Total risk based capital ratio	10.50%	8.00%
Tier 1 leverage ratio		4.00%
Capital conservation buffer ratio		2.50%
Common equity Tier 1 risk-based capital ratio	7.00%
Minimum capital conservation buffer	0.625%
Total assets		$ 15,000,000,000
Common equity tier 1 capital assets		250,000,000,000
Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total assets		$ 10,000,000,000