Earnings Per Share - Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share [Abstract]
Net income from continuing operations	$ 1,466	$ 309	$ 254
Less: Net income (loss) attributable to non-controlling interests	0	2	(4)
Less: Undistributed earnings attributable to participating stockholders	8	3	2
Less: Premium on retirement of preferred stock	28	0	0
Net income from continuing operations attributable to Mr. Cooper common stockholders	1,430	304	256
Net (loss) income from discontinued operations	(12)	(2)	16
Less: Undistributed earnings from discontinued operations attributable to participating stockholders	0	0	0
Net (loss) income from discontinued operations attributable to Mr. Cooper common stockholders	(12)	(2)	16
Net income	1,454	307	270
Less: Net income (loss) attributable to non-controlling interests	0	2	(4)
Net income attributable to Mr. Cooper	1,454	305	274
Less: Undistributed earnings attributable to participating stockholders	8	3	2
Net income attributable to common stockholders	$ 1,418	$ 302	$ 272
Earnings Per Share, Basic and Diluted [Abstract]
Income (Loss) from Continuing Operations, Per Basic Share	$ 17.39	$ 3.33	$ 2.81
Income (Loss) from Continuing Operations, Per Diluted Share	16.67	3.22	2.78
Discontinued Operation, Income (Loss) from Discontinued Operation, Net of Tax, Per Basic Share	(0.15)	(0.02)	0.18
Discontinued Operation, Income (Loss) from Discontinued Operation, Net of Tax, Per Diluted Share	(0.14)	(0.02)	0.17
Basic (in dollars per share)	17.24	3.31	2.99
Diluted (in dollars per share)	$ 16.53	$ 3.20	$ 2.95
Weighted average shares of common stock outstanding (in thousands):
Basic (in shares)	82,247	91,312	91,035
Dilutive effect of stock awards (in shares)	3,067	2,343	270
Dilutive effect of participating securities (in shares)	492	839	839
Diluted (in shares)	85,806	94,494	92,144