Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Net income (loss) attributable to Mr. Cooper	$ 73	$ (87)	$ (95)	$ (273)
Less: Undistributed earnings attributable to participating stockholders	1	0	0	0
Net income (loss) attributable to common stockholders	$ 72	$ (87)	$ (95)	$ (273)
Net income (loss) per common share attributable to Mr. Cooper:
Basic (in dollars per share)	$ 0.78	$ (0.96)	$ (1.04)	$ (3.00)
Diluted (in dollars per share)	$ 0.77	$ (0.96)	$ (1.04)	$ (3.00)
Weighted average shares of common stock outstanding (in thousands):
Basic (in shares)	91,997	91,054	91,691	90,978
Dilutive effect of stock awards (in shares)	176	0	0	0
Dilutive effect of participating securities (in shares)	839	0	0	0
Diluted (in shares)	93,012	91,054	91,691	90,978