Fair Value of Assets and Liabilities - Carrying Value and Estimated Fair Value of Senior Notes (Details) - Senior Notes - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Euro Senior Notes, Series A due 2023 | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Long-term debt fair value	$ 123,605	$ 124,716
Euro Senior Notes, Series A due 2023 | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Long-term debt fair value	122,830	122,270
Euro Senior Notes, Series B due 2028 | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Long-term debt fair value	100,363	101,265
Euro Senior Notes, Series B due 2028 | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Long-term debt fair value	87,722	87,119
U.S. Senior Notes, Series B due 2027 | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Long-term debt fair value	100,000	100,000
U.S. Senior Notes, Series B due 2027 | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Long-term debt fair value	92,866	93,764
U.S. Senior Notes, Series A due 2025 | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Long-term debt fair value	50,000	50,000
U.S. Senior Notes, Series A due 2025 | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Long-term debt fair value	48,338	48,145
U.S. Senior Notes, Series B due 2030 | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Long-term debt fair value	125,000	125,000
U.S. Senior Notes, Series B due 2030 | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Long-term debt fair value	109,188	112,028
U.S. Senior Notes, due 2032 | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Long-term debt fair value	100,000	100,000
U.S. Senior Notes, due 2032 | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Long-term debt fair value	$ 86,977	$ 90,131