Earnings Per Share - Computation of Basic and Diluted Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Earnings Per Share [Abstract]
Net income from continuing operations	$ 151	$ 427	$ 809	$ 986
Less: Undistributed earnings from continuing operations attributable to participating stockholders	0	4	0	9
Net income from continuing operations attributable to Mr. Cooper common stockholders	151	423	809	977
Net income from discontinued operations	0	12	0	14
Less: Undistributed earnings from discontinued operations attributable to participating stockholders	0	0	0	0
Net income from discontinued operations attributable to Mr. Cooper common stockholders	0	12	0	14
Net income	151	439	809	1,000
Less: Undistributed earnings attributable to participating stockholders	0	4	0	9
Net income attributable to common stockholders	$ 151	$ 435	$ 809	$ 991
Earnings Per Share, Basic [Abstract]
Income (Loss) from Continuing Operations, Per Basic Share	$ 2.08	$ 4.91	$ 11.04	$ 11.13
Income (Loss) from Continuing Operations, Per Diluted Share	2.03	4.72	10.74	10.65
Discontinued Operation, Income (Loss) from Discontinued Operation, Net of Tax, Per Basic Share	0	0.14	0	0.16
Discontinued Operation, Income (Loss) from Discontinued Operation, Net of Tax, Per Diluted Share	0	0.13	0	0.15
Basic (in dollars per share)	2.08	5.05	11.04	11.29
Diluted (in dollars per share)	$ 2.03	$ 4.85	$ 10.74	$ 10.80
Weighted average shares of common stock outstanding (in thousands):
Basic (in shares)	72,709	86,142	73,278	87,791
Dilutive effect of stock awards	1,618	2,664	2,052	3,123
Dilutive effect of participating securities	0	839	0	839
Diluted	74,327	89,645	75,330	91,753