Fair Value Measurements and Derivative Instruments (Available-for-sale Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized cost	$ 257,298	$ 260,145
Gross unrealized gains	1	11
Gross unrealized losses	(47,581)	(51,890)
Estimated fair value	209,718	208,266
Government and related securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized cost	35,263	35,744
Gross unrealized gains	0	11
Gross unrealized losses	(7,442)	(8,210)
Estimated fair value	27,821	27,545
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized cost	66,020	66,300
Gross unrealized gains	1	0
Gross unrealized losses	(12,414)	(13,981)
Estimated fair value	53,607	52,319
Commingled fixed income securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized cost	1,759	1,749
Gross unrealized gains	0	0
Gross unrealized losses	(206)	(229)
Estimated fair value	1,553	1,520
Mortgage-backed / asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized cost	154,256	156,352
Gross unrealized gains	0	0
Gross unrealized losses	(27,519)	(29,470)
Estimated fair value	$ 126,737	$ 126,882