Unaudited Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Millions	Total	Preferred Stock	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Share Amount	Total Nationstar Stockholders’ Equity and Mr. Cooper Stockholders’ Equity, respectively	Non-controlling Interests
Beginning of Period, shares at Dec. 31, 2017		0	97,728
Beginning of Period at Dec. 31, 2017	$ 1,722	$ 0	$ 1	$ 1,131	$ 731	$ (148)	$ 1,715	$ 7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued / (surrendered) under incentive compensation plan, shares			435
Shares issued / (surrendered) under incentive compensation plan	(6)			(4)		(2)	(6)
Share-based compensation	8			8			8
Dividends to non-controlling interests	(1)			5			5	(6)
Net income (loss)	218				218		218	0
Ending of Period at Jun. 30, 2018	1,941	$ 0	$ 1	1,140	949	(150)	1,940	1
Ending of Period, shares at Jun. 30, 2018		0	98,163
Beginning of Period, shares at Mar. 31, 2018		0	98,193
Beginning of Period at Mar. 31, 2018	1,882	$ 0	$ 1	1,131	891	(148)	1,875	7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued / (surrendered) under incentive compensation plan, shares			(30)
Shares issued / (surrendered) under incentive compensation plan	(2)			0		(2)	(2)
Share-based compensation	4			4			4
Dividends to non-controlling interests	(1)			5			5	(6)
Net income (loss)	58				58		58	0
Ending of Period at Jun. 30, 2018	1,941	$ 0	$ 1	1,140	949	(150)	1,940	1
Ending of Period, shares at Jun. 30, 2018		0	98,163
Beginning of Period, shares at Dec. 31, 2018		1,000	90,821
Beginning of Period at Dec. 31, 2018	1,945	$ 0	$ 1	1,093	848	0	1,942	3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued / (surrendered) under incentive compensation plan, shares			240
Shares issued / (surrendered) under incentive compensation plan	(2)			(2)			(2)
Share-based compensation	9			9			9
Net income (loss)	(274)				(273)		(273)	(1)
Ending of Period at Jun. 30, 2019	1,678	$ 0	$ 1	1,100	575	0	1,676	2
Ending of Period, shares at Jun. 30, 2019		1,000	91,061
Beginning of Period, shares at Mar. 31, 2019		1,000	91,042
Beginning of Period at Mar. 31, 2019	1,761	$ 0	$ 1	1,095	662	0	1,758	3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued / (surrendered) under incentive compensation plan, shares			19
Shares issued / (surrendered) under incentive compensation plan	0			0			0
Share-based compensation	5			5			5
Net income (loss)	(88)				(87)		(87)	(1)
Ending of Period at Jun. 30, 2019	$ 1,678	$ 0	$ 1	$ 1,100	$ 575	$ 0	$ 1,676	$ 2
Ending of Period, shares at Jun. 30, 2019		1,000	91,061