Stockholders' Equity - Accumulated Other Comprehensive Income/(Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Components of accumulated other comprehensive income/(loss)
Beginning balance	$ 2,018,606	$ 2,348,955	$ 1,988,849	$ 2,542,848
OCI before reclassifications	(6,805)	(4,937)	(7,921)	(8,659)
Amounts reclassified from AOCI	0	0	0	0
Other Comprehensive (Loss)	(6,805)	(4,937)	(7,921)	(8,659)
Ending balance	1,944,769	2,146,388	1,944,769	2,146,388
Total  AOCI
Components of accumulated other comprehensive income/(loss)
Beginning balance	20,225	41,856	21,341	45,578
Ending balance	13,420	36,919	13,420	36,919
Net Unrealized Gain/(Loss) on AFS Securities
Components of accumulated other comprehensive income/(loss)
Beginning balance	20,225	41,856	21,341	46,833
OCI before reclassifications	(6,805)	(4,937)	(7,921)	(9,914)
Amounts reclassified from AOCI	0	0	0	0
Other Comprehensive (Loss)	(6,805)	(4,937)	(7,921)	(9,914)
Ending balance	13,420	36,919	13,420	36,919
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 (Loss)	0	0	0	1,255
Ending balance	$ 0	$ 0	$ 0	$ 0