Summary of Significant Policies (LIHTC Restatement) (Detail) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
		Dec. 31, 2018		Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2016
Prior Period Adjustments Restatement
Other assets	[2]	$ 7,372	[1]	$ 7,372	[1]	$ 6,863
Accrued taxes, interest and expenses		1,562	[1]	1,562	[1]	1,465
Retained earnings	[1]	16,578		16,578		14,957
Total noninterest expense		3,928				3,782		$ 3,760
Income (Loss) Before Income Taxes		2,765				2,979		2,208
Applicable income tax expense		572				799		665
Net income (loss)		$ 2,193		2,193		$ 2,180	[1]	$ 1,543	[1]	$ 1,543
Earnings per share - basic	[1]	$ 3.11				$ 2.86		$ 1.92
Earnings per share - diluted	[1]	$ 3.06				$ 2.81		$ 1.91
Restatement Adjustment
Prior Period Adjustments Restatement
Other assets		$ (91)		(91)		$ (112)		$ (97)		(97)
Accrued taxes, interest and expenses		54		54		53		54		54
Retained earnings		(145)		(145)		(165)		(151)		(151)
Total noninterest expense		(175)				(208)		(143)
Income (Loss) Before Income Taxes		175				208		143
Applicable income tax expense		155				222		160
Net income (loss)		$ 20				$ (14)		$ (17)
Earnings per share - basic		$ 0.01				$ (0.02)		$ (0.03)
Earnings per share - diluted		$ 0.01				$ (0.02)		$ (0.02)
Originally Reported
Prior Period Adjustments Restatement
Other assets		$ 7,463		7,463		$ 6,975		$ 7,844		7,844
Accrued taxes, interest and expenses		1,508		1,508		1,412		1,800		1,800
Retained earnings		16,723		16,723		15,122		13,441		13,441
Total noninterest expense		4,103				3,990		3,903
Income (Loss) Before Income Taxes		2,590				2,771		2,065
Applicable income tax expense		417				577		505
Net income (loss)		$ 2,173				$ 2,194		$ 1,560
Earnings per share - basic		$ 3.1				$ 2.88		$ 1.95
Earnings per share - diluted		$ 3.05				$ 2.83		$ 1.93
Adjusted
Prior Period Adjustments Restatement
Other assets		$ 7,372		7,372		$ 6,863		$ 7,747		7,747
Accrued taxes, interest and expenses		1,562		1,562		1,465		1,854		1,854
Retained earnings		16,578		$ 16,578		14,957		13,290		$ 13,290
Total noninterest expense		3,928				3,782		3,760
Income (Loss) Before Income Taxes		2,765				2,979		2,208
Applicable income tax expense		572				799		665
Net income (loss)		$ 2,193				$ 2,180		$ 1,543
Earnings per share - basic		$ 3.11				$ 2.86		$ 1.92
Earnings per share - diluted		$ 3.06				$ 2.81		$ 1.91

[1] Effective in the fourth quarter of 2018, Fifth Third retrospectively applied a change in its accounting policy for investments in affordable housing projects that qualify for LIHTC in accordance with ASU 2014-01. Refer to Note 1 for additional information.

[2] Includes $ 40 and $ 62 of other short-term investments, $ 668 and $ 1,297 of portfolio loans and leases, $ (4) and $ (6) of ALLL, $ 5 and $ 7 of other assets, $ 1 and $ 2 of other liabilities and $ 606 and $ 1,190 of long-term debt from consolidated VIEs that are included in their respec tive captions above at December 31, 2018 and 2017 , respectively. For further information, refer to Note 10 .