CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Assets
Residential mortgage investments pledged	$ 13,090,000	$ 13,540,000
Stockholders' equity
Preferred stock, par value (in dollars per share)	$ 0.10	$ 0.10
Preferred stock, shares authorized (in shares)	100,000	100,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	250,000	250,000
Common stock, shares issued (in shares)	95,989	95,825
Common stock, shares outstanding (in shares)	95,989	95,825
Cumulative Redeemable Preferred Stock, Series E [Member]
Stockholders' equity
Preferred stock, shares issued (in shares)	8,204	8,156
Preferred stock, shares outstanding (in shares)	8,204	8,156
Preferred stock, dividend rate	7.50%	7.50%
Preferred stock, aggregate liquidation preference	$ 205,107	$ 203,902