Borrowings - Assets Sold Under Agreement to Repurchase (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Apr. 01, 2020	Dec. 31, 2019
During the period:
Total interest expense	$ 17,487,000	$ 19,645,000	$ 43,171,000	$ 28,280,000
Carrying value:
Unpaid principal balance	3,769,495,000		3,769,495,000			$ 4,141,680,000
Unamortized debt issuance costs and premiums	(10,180,000)		(10,180,000)			(627,000)
Unamortized debt issuance costs	(10,180,000)		(10,180,000)			(627,000)
Total loans sold under agreements to repurchase	$ 3,759,315,000		$ 3,759,315,000			$ 4,141,053,000
Weighted average interest rate (as a percent)	2.13%		2.13%			3.29%
Available borrowing capacity committed						$ 125,810,000
Available borrowing capacity uncommitted	$ 2,090,894,000		$ 2,090,894,000			782,510,000
Available borrowing capacity	2,090,894,000		2,090,894,000			908,320,000
Servicing advances	197,094,000		197,094,000			207,460,000
Margin deposits placed with counterparties	4,375,000		4,375,000			5,000,000
Loans held for sale
Carrying value:
Fair value of assets pledged to secure	4,315,116,000		4,315,116,000			4,322,789,000
Mortgage servicing rights
Carrying value:
Fair value of assets pledged to secure	2,188,921,000		2,188,921,000			2,902,721,000
Servicing advances
Carrying value:
Fair value of assets pledged to secure	197,094,000		197,094,000			207,460,000
Financing receivable
Carrying value:
Fair value of assets pledged to secure	90,101,000		90,101,000			$ 107,512,000
Deposits
Carrying value:
Fair value of assets pledged to secure	125,017,000		125,017,000
Note Payable
During the period:
Average balance of assets sold under agreements to repurchase	1,300,000,000	1,300,000,000	1,300,000,000	1,300,000,000
Carrying value:
Amortization of debt issuance costs	451,000	445,000	896,000	889,000
Assets sold under agreements to repurchase
During the period:
Average balance of assets sold under agreements to repurchase	$ 2,529,217,000	$ 1,988,920,000	$ 2,833,444,000	$ 1,715,846,000
Weighted-average interest rate (as a percent)	2.32%	4.35%	2.74%	4.40%
Total interest expense	$ 17,487,000	$ 19,645,000	$ 43,171,000	$ 28,280,000
Maximum daily amount outstanding	3,769,495,000	2,748,375,000	3,769,495,000	2,748,375,000
Carrying value:
Amortization of debt issuance costs	$ 2,800,000		$ 4,400,000
Amortization of premium		2,000,000.0		9,400,000
Amount of Master Repurchase Agreement incentives to refinance include in interest expense		$ 3,900,000		$ 13,200,000
PLS | Credit Suisse First Boston Mortgage Capital LLC | Note Payable
Mortgage loans sold under agreement to repurchase
Maximum loan amount					$ 600,000,000