Stockholders' Equity - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2015 USD ($)
2015 [Member]
Stockholders Equity [Line Items]
Implementation of the deductions and other adjustments to CET1	4 years
Implementation of the deductions and other adjustments to CET1, Percentage	40.00%
After 2015 [Member]
Stockholders Equity [Line Items]
Implementation of the deductions and other adjustments to CET1, Additional Percentage	20.00%
2016 [Member]
Stockholders Equity [Line Items]
Implementation of the capital conservation buffer, Percentage	0.625%
Capital conservation buffer implementation phase-out period	4 years
2019 [Member]
Stockholders Equity [Line Items]
Capital Conservation Buffer Maximum Level	2.50%
Maximum [Member]
Stockholders Equity [Line Items]
Quantitative limit for trust preferred securities to be included in tier 1 capital	$ 15,000,000,000