Estimated Fair Values (Assets and Liabilities Carried at Fair Value on a Recurring Basis Significant Unobservable Inputs) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Corporate bonds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 316,624	$ 69,685
Purchases	30,878	242,595
Unrealized net losses (gains) included in other comprehensive income	6,391	2,898
Amounts included in net income	2,555	(336)
Transfers in	0	1,782
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	(102,065)	0
Sales / Calls	(46,981)	0
Ending balance	207,402	316,624
Investment securities available for sale	207,402	316,624
Corporate Bond Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Transfers in		$ 1,800
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	$ (102,100)