Capital One Financial Corporation (Parent Company Only) - Balance Sheets (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Assets:
Cash and cash equivalents	$ 30,856	$ 21,746
Other assets	26,548	22,816
Total assets	455,249	432,381
Liabilities:
Senior and subordinated notes	30,826	27,219
Other liabilities	20,433	17,005
Total liabilities	402,667	371,352
Stockholders’ equity:
Stockholders' Equity Attributable to Parent	52,582	61,029	$ 60,204	$ 58,011
Total liabilities and stockholders’ equity	455,249	432,381
Parent Company
Assets:
Cash and cash equivalents	22,006	16,910
Investments in subsidiaries	50,523	57,600
Receivables From Subsidiaries	6,710	7,849
Securities available for sale (amortized cost of $87.0 billion and $94.9 billion and allowance for credit losses of $3 million and $1 million as of December 31, 2022 and 2021, respectively)	395	513
Other assets	2,281	1,330
Total assets	81,915	84,202
Liabilities:
Senior and subordinated notes	28,970	23,017
Other liabilities	363	156
Total liabilities	29,333	23,173
Stockholders’ equity:
Stockholders' Equity Attributable to Parent	52,582	61,029
Total liabilities and stockholders’ equity	$ 81,915	$ 84,202