Capital - Additional Information (Details) - USD ($)		3 Months Ended				12 Months Ended
		Dec. 31, 2015		Mar. 31, 2015	Dec. 31, 2014	Dec. 31, 2015		Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2011	Dec. 31, 2009	Sep. 22, 2011	Dec. 31, 2008	Sep. 30, 2006
Schedule of Capitalization, Equity [Line Items]
Stock Issued During Period, Value, New Issues								$ 496,000,000
Common Stock, Dividends, Per Share, Cash Paid		$ 0.20			$ 0.24	$ 0.92		$ 0.70	$ 0.35
Dividends, Common Stock, Cash						$ (475,000,000)		$ (371,000,000)	$ (188,000,000)
Dividends, Preferred Stock, Cash						$ (64,000,000)		(42,000,000)	(37,000,000)
Dividend Per Quarter Threshold Prior To Tenth Anniversay Triggering Execise Of Warrants		$ 0.54				$ 0.54
Cash Reserve Deposit Required and Made		$ 1,000,000,000			$ 1,500,000,000	$ 1,000,000,000		$ 1,500,000,000
Common Equity Tier 1 to Risk Weighted Assets	[1]	9.96%				9.96%
Capital to Risk Weighted Assets		12.54%	[1]		12.51%	12.54%	[1]	12.51%
Tier One Leverage Capital to Average Assets		9.69%	[1]		9.64%	9.69%	[1]	9.64%
Document Period End Date						Dec. 31, 2015
Preferred Stock, Shares Authorized		50,000,000			50,000,000	50,000,000		50,000,000
Stock Issued During Period, Value, New Issues						$ 0		$ 496,000,000	$ 0
Class of Warrant or Right, Outstanding		13,900,000				13,900,000
Common Stock [Member]
Schedule of Capitalization, Equity [Line Items]
Stock Repurchased During Period, Value				$ 115,000,000		$ 525,000,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount		$ 350,000,000				$ 350,000,000
Stock Repurchased During Period, Shares						12,700,000
Series A Preferred Stock [Member]
Schedule of Capitalization, Equity [Line Items]
Preferred Stock, Dividends, Per Share, Cash Paid						$ 4,056		$ 4,056	$ 4,056
Preferred Stock, Shares Issued														5,000
Preferred Stock, No Par Value														$ 0
Preferred Stock, Liquidation Preference, Value														$ 100,000
Declared And Accrued Preferred Stock Dividend Basis Spread on Variable Rate						0.53%
Declared And Accrued Preferred Stock Dividend Fixed Rate						4.00%
Stock Redeemed or Called During Period, Shares											3,275
Preferred Stock, Redemption Price Per Share														$ 100,000
Series B Preferred Stock [Member]
Schedule of Capitalization, Equity [Line Items]
Preferred Stock, Dividends, Per Share, Cash Paid						$ 4,056		4,056	4,056
Preferred Stock, Shares Authorized										5,010
Preferred Stock, Shares Issued										1,025
Preferred Stock, No Par Value										$ 0
Preferred Stock, Liquidation Preference, Value										$ 100,000
Declared And Accrued Preferred Stock Dividend Basis Spread on Variable Rate						0.65%
Declared And Accrued Preferred Stock Dividend Fixed Rate						4.00%
Preferred Stock, Redemption Price Per Share		$ 100,000				$ 100,000
Series E Preferred Stock [Member]
Schedule of Capitalization, Equity [Line Items]
Preferred Stock, Dividends, Per Share, Cash Paid						5,875		5,875	$ 5,793
Preferred Stock, Shares Authorized									5,000
Preferred Stock, Shares Issued									4,500
Preferred Stock, No Par Value									$ 0
Preferred Stock, Liquidation Preference, Value									$ 100,000
Declared And Accrued Preferred Stock Dividend Fixed Rate									5.88%
Preferred Stock, Redemption Price Per Share									$ 100,000
Series F Preferred Stock [Member]
Schedule of Capitalization, Equity [Line Items]
Preferred Stock, Dividends, Per Share, Cash Paid						$ 6,219		$ 0
Preferred Stock, Shares Issued		5,000				5,000
Preferred Stock, No Par Value		$ 0				$ 0
Preferred Stock, Liquidation Preference, Value		$ 100,000				$ 100,000
Declared And Accrued Preferred Stock Dividend Basis Spread on Variable Rate						3.86%
Declared And Accrued Preferred Stock Dividend Fixed Rate						5.63%
Preferred Stock, Redemption Price Per Share		$ 100,000				$ 100,000
Sun Trust Bank [Member]
Schedule of Capitalization, Equity [Line Items]
Retained Earnings, Unappropriated		$ 2,700,000,000			$ 2,900,000,000	$ 2,700,000,000		$ 2,900,000,000
Parent Company [Member]
Schedule of Capitalization, Equity [Line Items]
Dividends, Preferred Stock, Cash						(64,000,000)		(42,000,000)	$ (37,000,000)
Stock Issued During Period, Value, New Issues						0		496,000,000	$ 0
Parent Company [Member] | Junior Subordinated Debt [Member]
Schedule of Capitalization, Equity [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Amount					$ 627,000,000			$ 627,000,000
Series A [Member]
Schedule of Capitalization, Equity [Line Items]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights													6,000,000
Class of Warrant or Right, Exercise Price of Warrants or Rights													$ 33.70
warrants purchased										4,000,000
Payments for Repurchase of Warrants										$ 11,000,000
Series B [Member]
Schedule of Capitalization, Equity [Line Items]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights													12,000,000
Class of Warrant or Right, Exercise Price of Warrants or Rights													$ 44.15
Warrant [Member]
Schedule of Capitalization, Equity [Line Items]
Class of Warrant or Right, Outstanding												17,900,000
Long-term Debt [Member] | Parent Company [Member] | Junior Subordinated Debt [Member]
Schedule of Capitalization, Equity [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Amount		$ 627,000,000				$ 627,000,000
Minimum [Member]
Schedule of Capitalization, Equity [Line Items]
Common Equity Tier 1 to Risk Weighted Assets		4.50%				4.50%
Tier One Risk Based Capital to Risk Weighted Assets		6.00%				6.00%
Capital to Risk Weighted Assets		8.00%				8.00%
Tier One Leverage Capital to Average Assets		4.00%				4.00%
Capital Required for Capital Adequacy to Risk Weighted Assets		2500000.00%				2500000.00%

[1] Basel III Final Rules became effective on January 1, 2015; thus, CET1 is not applicable ("N/A") in periods ending prior to January 1, 2015 and Basel I Tier 1 common equity is N/A in periods ending after January 1, 2015. Tier 1 capital, Total capital, and Leverage ratio for periods ended prior to January 1, 2015 were calculated under Basel I.