Securities Fair Value Option Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair Value Option Securities [Line Items]
Fair value option securities	$ 1,098,577	$ 283,235
Fair Value Option Securities Unrealized Gain or Loss	14,061	2,766
U.S. Treasury [Member]
Fair Value Option Securities [Line Items]
Fair value option securities	9,917	0
Fair Value Option Securities Unrealized Gain or Loss	(48)	0
Residential agency mortgage-backed securities [Member]
Fair Value Option Securities [Line Items]
Fair value option securities	1,088,660	283,235
Fair Value Option Securities Unrealized Gain or Loss	$ 14,109	$ 2,766