CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (Parenthetical) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Preferred Stock, par value (usd per share)	$ 0.01	$ 0.01
Preferred Stock, shares authorized (shares)	100,000,000	100,000,000
Common stock, par value (usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized (shares)	300,000,000	300,000,000
Common stock, shares issued (shares)	187,006,450	187,809,288
Common stock, shares outstanding (shares)	187,006,450	187,809,288
Repurchase Agreements | Residential Mortgage-Backed Securities
Securities pledged as collateral	$ 10,626,383,000	$ 8,788,680,000
Variable Interest Entities, Primary Beneficiary, Aggregated Disclosure
Assets	14,455,778,000	14,987,464,000
Liabilities	9,559,149,000	9,631,820,000
Securitized Loans | Non-agency MBS
Securities pledged as collateral	1,300,000,000	1,600,000,000
Securitized Loans | Loans Held for Investment at Fair Value
Securities pledged as collateral	$ 13,000,000,000	$ 13,300,000,000
Preferred Class A
Preferred Stock, dividend rate (percent)	8.00%	8.00%
Preferred Stock, shares issued (shares)	5,800,000	5,800,000
Preferred Stock, shares outstanding (shares)	5,800,000	5,800,000
Preferred Stock, liquidation preference	$ 145,000	$ 145,000
Preferred Class B
Preferred Stock, dividend rate (percent)	8.00%	8.00%
Preferred Stock, shares issued (shares)	13,000,000	13,000,000
Preferred Stock, shares outstanding (shares)	13,000,000	13,000,000
Preferred Stock, liquidation preference	$ 325,000	$ 325,000