Stock-Related Matters (Details)	1 Months Ended				2 Months Ended	4 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2017 USD ($) shares	Jan. 31, 2016 USD ($) shares	Jun. 30, 2015 shares	Mar. 31, 2015 shares	Dec. 31, 2015 shares	Aug. 31, 2017 USD ($) shares	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($) shares	Nov. 05, 2017 USD ($)	May 03, 2017 USD ($)
Share Repurchases [Line Items]
Payment for repurchase of common stock								$ 301,000,000	$ 23,000,000	$ 77,000,000
Aggregate amount of PHH's common stock repurchase								$ 301,000,000	$ 23,000,000	$ 78,000,000
Maximum ratio of unsecured indebtedness to tangible net worth								1.25
Aggregate restricted net assets of subsidiaries								$ 102,000,000
Accelerated Stock Repurchase Programs
Share Repurchases [Line Items]
Repurchase of common stock (in shares) | shares				1,574,252
Open Market Share Repurchase Program
Share Repurchases [Line Items]
Shares authorized for repurchase (in dollars)						$ 300,000,000					$ 100,000,000	$ 100,000,000
Payment for repurchase of common stock							$ 34,000,000
Repurchase of common stock (in shares) | shares		1,508,772			4,841,267	2,450,466				4,841,267
Aggregate amount of PHH's common stock repurchase		$ 23,000,000								$ 77,000,000
Modified Dutch auction self-tender offer
Share Repurchases [Line Items]
Payment for repurchase of common stock	$ 267,000,000
Repurchase of common stock (in shares) | shares	18,762,962
Convertible Notes Due 2017
Share Repurchases [Line Items]
Number of shares issued from conversion of notes (in shares) | shares			10,075,653
Unsecured credit facilities | Minimum
Share Repurchases [Line Items]
Net worth threshold, base amount								250,000,000
Covenant net worth on last day of each fiscal quarter after current year								$ 150,000,000