Stockholders' Equity (Details 2) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Components of accumulated other comprehensive income/(loss)
Amounts reclassified from AOCI	$ 14,935	$ 7,314	$ 31,315	$ 27,280
Net OCI during the period	(2,156)	79,805	56,544	57,680
Net Unrealized Gain/(Loss) on AFS Securities
Components of accumulated other comprehensive income/(loss)
Balance at beginning of period	668,223	625,697	620,403	585,250
OCI before reclassifications	6,988	64,350	71,188	124,763
Amounts reclassified from AOCI	(14,935)	(7,314)	(31,315)	(27,280)
Net OCI during the period	(7,947)	57,036	39,873	97,483
Balance at end of period	660,276	682,733	660,276	682,733
Net (Loss)/Gain on Swaps
Components of accumulated other comprehensive income/(loss)
Balance at beginning of period	(35,841)	(131,971)	(46,721)	(69,399)
OCI before reclassifications	5,791	22,769	16,671	(39,803)
Amounts reclassified from AOCI	0	0	0	0
Net OCI during the period	5,791	22,769	16,671	(39,803)
Balance at end of period	(30,050)	(109,202)	(30,050)	(109,202)
Total AOCI
Components of accumulated other comprehensive income/(loss)
Balance at beginning of period	632,382	493,726	573,682	515,851
OCI before reclassifications	12,779	87,119	87,859	84,960
Amounts reclassified from AOCI	(14,935)	(7,314)	(31,315)	(27,280)
Net OCI during the period	(2,156)	79,805	56,544	57,680
Balance at end of period	$ 630,226	$ 573,531	$ 630,226	$ 573,531