Condensed Consolidated Statements of Shareholders’ Equity - USD ($) $ in Millions	Total		Net impact of adoption of ASU 2016-13	Balance post-adoption	Common Stock	Common Stock Balance post-adoption	Additional Paid-in Capital	Additional Paid-in Capital Balance post-adoption	Total Accumulated Other Comprehensive Income (Loss)	Total Accumulated Other Comprehensive Income (Loss) Balance post-adoption	Retained Earnings		Retained Earnings Net impact of adoption of ASU 2016-13	[1]	Retained Earnings Balance post-adoption	OMFC	OMFC Balance post-adoption	OMFC Common Stock	OMFC Common Stock Balance post-adoption	OMFC Additional Paid-in Capital	OMFC Additional Paid-in Capital Balance post-adoption	OMFC Total Accumulated Other Comprehensive Income (Loss)	OMFC Total Accumulated Other Comprehensive Income (Loss) Balance post-adoption	OMFC Retained Earnings	OMFC Retained Earnings Balance post-adoption	SMHC OMFC	SMHC OMFC Additional Paid-in Capital
Balance at beginning of period at Dec. 31, 2018	$ 3,799				$ 1		$ 1,681		$ (34)		$ 2,151					$ 4,021		$ 5		$ 2,110		$ (34)		$ 1,940
Increase (Decrease) in Stockholders' Equity
Contribution of SCHC to OMFC from SFI																										$ 34	$ 34
Share-based compensation expense, net of forfeitures	10						10									10				10
Withholding tax on share-based compensation	(5)						(5)									(5)				(5)
Other comprehensive income (loss)	72								72							72						72
Merger of SFI with OMFC																(408)				(408)
Cash contribution from OMH																144				144
Cash dividends	(376)	[1]									(376)	[1]				(376)								(376)
Net income	594										594					597								597
Balance at end of period at Sep. 30, 2019	$ 4,094				1		1,686		38		2,369					4,089		5		1,885		38		2,161
Increase (Decrease) in Stockholders' Equity
Dividends declared (in dollars per share)	$ 2.75
Balance at beginning of period at Dec. 31, 2018	$ 3,799				1		1,681		(34)		2,151					4,021		5		2,110		(34)		1,940
Balance at end of period at Dec. 31, 2019	$ 4,330		$ (828)	$ 3,502	1	$ 1	1,689	$ 1,689	44	$ 44	2,596		$ (828)		$ 1,768	4,325	$ 3,497	5	$ 5	1,888	$ 1,888	44	$ 44	2,388	$ 1,560
Increase (Decrease) in Stockholders' Equity
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Balance at beginning of period at Jun. 30, 2019	$ 4,141				1		1,683		28		2,429					4,404		5		2,146		28		2,225
Increase (Decrease) in Stockholders' Equity
Share-based compensation expense, net of forfeitures	3						3									3				3
Other comprehensive income (loss)	10								10							10						10
Merger of SFI with OMFC																(408)				(408)
Cash contribution from OMH																144				144
Cash dividends	(308)	[1]									(308)	[1]				(308)								(308)
Net income	248										248					244								244
Balance at end of period at Sep. 30, 2019	$ 4,094				1		1,686		38		2,369					4,089		5		1,885		38		2,161
Increase (Decrease) in Stockholders' Equity
Dividends declared (in dollars per share)	$ 2.25
Balance at beginning of period at Dec. 31, 2019	$ 4,330		$ (828)	$ 3,502	1	$ 1	1,689	$ 1,689	44	$ 44	2,596		$ (828)		$ 1,768	4,325	$ 3,497	5	$ 5	1,888	$ 1,888	44	$ 44	2,388	$ 1,560
Increase (Decrease) in Stockholders' Equity
Common stock repurchased and retired	(45)						(45)
Share-based compensation expense, net of forfeitures	13						13									13				13
Withholding tax on share-based compensation	(6)						(6)									(6)				(6)
Other comprehensive income (loss)	35								35							35						35
Cash dividends	(747)	[1]									(747)	[1]				(788)								(788)
Net income	371										371					371								371
Balance at end of period at Sep. 30, 2020	$ 3,123				1		1,651		79		1,392					3,122		5		1,895		79		1,143
Increase (Decrease) in Stockholders' Equity
Dividends declared (in dollars per share)	$ 5.49
Balance at beginning of period at Jun. 30, 2020	$ 3,171				1		1,648		65		1,457					3,170		5		1,892		65		1,208
Increase (Decrease) in Stockholders' Equity
Share-based compensation expense, net of forfeitures	3						3									3				3
Other comprehensive income (loss)	14								14							14						14
Cash dividends	(315)	[1]									(315)	[1]				(315)								(315)
Net income	250										250					250								250
Balance at end of period at Sep. 30, 2020	$ 3,123				$ 1		$ 1,651		$ 79		$ 1,392					$ 3,122		$ 5		$ 1,895		$ 79		$ 1,143
Increase (Decrease) in Stockholders' Equity
Dividends declared (in dollars per share)	$ 2.33

[1] Cash dividends declared were $2.33 per share and $2.25 per share during the three months ended September 30, 2020 and 2019, respectively, and $5.49 per share and $2.75 per share during the nine months ended September 30, 2020 and 2019, respectively.