Long-Term Debt Shelf Arrangements (Details) - USD ($) $ in Thousands		Feb. 01, 2023	Dec. 31, 2022		Dec. 31, 2021
Line of Credit Facility [Line Items]
Long-term Debt			$ (600,800)		$ (568,800)
Debt Instrument, Unused Borrowing Capacity, Amount	[1]		170,000
Prudential [Member]
Line of Credit Facility [Line Items]
Long-term Debt	[2]		(220,000)
Debt Instrument, Unused Borrowing Capacity, Amount	[2]		70,000
MetLife [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Face Amount		$ 200,000	150,000
Long-term Debt			(50,000)
Debt Instrument, Unused Borrowing Capacity, Amount			100,000
Aggregate Shelf Agreements [Member]
Line of Credit Facility [Line Items]
Long-term Debt	[1]		(270,000)
Aggregated Unfunded Commitments [Member]
Line of Credit Facility [Line Items]
Long-term Debt	[1]		(80,000)
Aggregated Unfunded Commitments [Member] | Prudential [Member]
Line of Credit Facility [Line Items]
Long-term Debt	[2]		(80,000)
Uncollateralized Senior Note Due April Two Thousand Thirty Two [Member]
Line of Credit Facility [Line Items]
Long-term Debt			$ (66,500)		(70,000)
Debt Instrument, Interest Rate, Stated Percentage			3.25%
Uncollateralized Senior Note Due August Two Thousand Thirty Nine [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			3.98%
Uncollateralized Senior Note Due July Two Thousand Thirty Five
Line of Credit Facility [Line Items]
Long-term Debt			$ (50,000)		(50,000)
Debt Instrument, Interest Rate, Stated Percentage			3.00%
Uncollateralized Senior Note Due August Two Thousand Thirty Five
Line of Credit Facility [Line Items]
Long-term Debt			$ (40,000)		$ (40,000)
Debt Instrument, Interest Rate, Stated Percentage			2.96%
Uncollateralized Senior Note Due March 14, 2038
Line of Credit Facility [Line Items]
Long-term Debt			$ (80,000)
Debt Instrument, Interest Rate, Stated Percentage			5.43%
Uncollateralized Senior Note Due March 14, 2038 | Prudential [Member]
Line of Credit Facility [Line Items]
Long-term Debt			$ (80,000)
Maximum [Member] | Prudential [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Face Amount		$ 405,000	370,000	[2]
Maximum [Member] | Aggregate Shelf Agreements [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Face Amount	[1]		$ 520,000

[1] 1) The amended Prudential and MetLife Shelf Agreements both expire in February 2026.

[2] (2) Unfunded commitments of $80.0 million reflects Senior Notes expected to be issued on or before March 14, 2023