CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Assets
Residential mortgage investments pledged	$ 12,980,000	$ 12,810,000
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)	95,698	95,989
Common stock, shares outstanding (in shares)	95,698	95,989
Cumulative Redeemable Preferred Stock, Series E [Member]
Stockholders’ equity
Preferred stock, shares issued (in shares)	10,329	8,234
Preferred stock, shares outstanding (in shares)	10,329	8,234
Preferred stock, dividend rate	7.50%	7.50%
Preferred stock, aggregate liquidation preference	$ 258,226	$ 205,849