REGULATORY MATTERS - Capital and Capital Ratio Information (Details) - USD ($) $ in Millions		Dec. 31, 2016		Dec. 31, 2015
Common Equity Tier 1 to Risk-Weighted Assets (Amount)
Actual	[1]	$ 13,822	[2]	$ 13,389
Minimum Capital Adequacy	[1]	6,348	[2]	5,134
Classification as Well-capitalized	[1],[3]	$ 8,051	[2]	$ 7,415
Common Equity Tier 1 to Risk-Weighted Assets (Ratio)
Actual	[1]	11.20%	[2]	11.70%
Minimum Capital Adequacy	[1]	5.125%	[2]	4.50%
Classification as Well-capitalized	[1],[3]	6.50%	[2]	6.50%
Tier 1 Capital to Risk-Weighted Assets (Amount)
Actual	[4]	$ 14,069	[2]	$ 13,636
Minimum Capital Adequacy	[4]	8,206	[2]	6,845
Classification as Well-capitalized	[3],[4]	$ 9,909	[2]	$ 9,127
Tier 1 Capital to Risk-Weighted Assets (Ratio)
Actual	[4]	11.40%	[2]	12.00%
Minimum Capital Adequacy	[4]	6.625%	[2]	6.00%
Classification as Well-capitalized	[3],[4]	8.00%	[2]	8.00%
Total Capital to Risk-Weighted Assets (Amount)
Actual	[5]	$ 17,347	[2]	$ 17,505
Minimum Capital Adequacy	[5]	10,683	[2]	9,127
Classification as Well-capitalized	[3],[5]	$ 12,386	[2]	$ 11,408
Total Capital to Risk-Weighted Assets (Ratio)
Actual	[5]	14.00%	[2]	15.30%
Minimum Capital Adequacy	[5]	8.625%	[2]	8.00%
Classification as Well-capitalized	[3],[5]	10.00%	[2]	10.00%
Tier 1 Capital to Average Assets (Leverage) (Amount)
Actual	[6]	$ 14,069		$ 13,636
Minimum Capital Adequacy	[6]	5,667		5,218
Classification as Well-capitalized	[3],[6]	$ 7,084		$ 6,523
Tier 1 Capital to Average Assets (Leverage) (Ratio)
Actual	[6]	9.90%		10.50%
Minimum Capital Adequacy	[6]	4.00%		4.00%
Classification as Well-capitalized	[3],[6]	5.00%		5.00%
Capital Conservation Buffer		0.625%

[1] “Common equity tier 1 capital ratio” represents CET1 capital divided by total risk-weighted assets as defined under Basel III Standardized approach.

[2] “Minimum Capital ratio” for 2016 includes capital conservation buffer of 0.625%.

[3] Presented for informational purposes. Prompt corrective action provisions apply only to insured depository institutions-in our case CBNA and CBPA.

[4] “Tier 1 capital ratio” is tier 1 capital, which includes CET1 capital plus non-cumulative perpetual preferred equity that qualifies as additional tier 1 capital, divided by total risk-weighted assets as defined under Basel III Standardized approach.

[5] “Total capital ratio” is total capital divided by total risk-weighted assets as defined under Basel III Standardized approach.

[6] “Tier 1 leverage ratio” is tier 1 capital divided by quarterly average total assets as defined under Basel III Standardized approach.