Stockholders' Equity - Accumulated Other Comprehensive Income/(Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Components of accumulated other comprehensive income/(loss)
Beginning balance	$ 1,944,769	$ 2,146,388	$ 1,988,849	$ 2,542,848
OCI before reclassifications	933	(5,851)	(6,988)	(14,510)
Amounts reclassified from AOCI	0	0	0	0
Other Comprehensive Income/(Loss)	933	(5,851)	(6,988)	(14,510)
Ending balance	1,848,516	2,033,931	1,848,516	2,033,931
Total  AOCI
Components of accumulated other comprehensive income/(loss)
Beginning balance	13,420	36,919	21,341	45,578
Ending balance	14,353	31,068	14,353	31,068
Net Unrealized Gain/(Loss) on AFS Securities
Components of accumulated other comprehensive income/(loss)
Beginning balance	13,420	36,919	21,341	46,833
OCI before reclassifications	933	(5,851)	(6,988)	(15,765)
Amounts reclassified from AOCI	0	0	0	0
Other Comprehensive Income/(Loss)	933	(5,851)	(6,988)	(15,765)
Ending balance	14,353	31,068	14,353	31,068
Net Unrealized Gain/(Loss) on Financing Agreements
Components of accumulated other comprehensive income/(loss)
Beginning balance	0	0	0	(1,255)
OCI before reclassifications	0	0	0	1,255
Amounts reclassified from AOCI	0	0	0	0
Other Comprehensive Income/(Loss)	0	0	0	1,255
Ending balance	$ 0	$ 0	$ 0	$ 0