REGULATORY MATTERS - Narrative (Details) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($) subsidiary $ / shares shares	Mar. 31, 2016 USD ($) $ / shares	Jan. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common share dividends (in Dollars per Share) | $ / shares	$ 0.14	$ 0.1
Common share dividends	$ 72	$ 53
Preferred share dividends	$ 7	$ 7
Treasury stock purchased (in shares) | shares	3,398,478
Treasury stock purchased	$ 130
Assets	$ 150,285			$ 149,520
Banking Subsidiaries
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Number of financial subsidiaries | subsidiary	2
CBNA subsidiaries
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Number of financial subsidiaries | subsidiary	2
Minimum | 2017 CCAR Plan
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Assets			$ 50,000
Maximum | 2017 CCAR Plan
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Assets			250,000
Maximum | 2017 CCAR Plan | Nonbank Subsidiaries
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Assets			$ 75,000