Fair Value Measurements Other Long-Term Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other long-term investments	$ 57,399	$ 27,294
Middle market
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Remaining life (In years)	10 years	10 years
Global equity market
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Remaining life (In years)	0 years	0 years
Term liquidity facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Remaining life (In years)	0 years	3 years
Late-stage growth
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Remaining life (In years)	6 years	7 years
Infrastructure
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Remaining life (In years)	12 years	12 years
Fair Value Measured at Net Asset Value Per Share | Private Equity Funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other long-term investments	$ 56,038	$ 11,923
Fair Value Measured at Net Asset Value Per Share | Private Equity Funds | Unfunded Loan Commitment
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other long-term investments	39,824	63,571
Fair Value Measured at Net Asset Value Per Share | Middle market
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other long-term investments	21,947	10,542
Fair Value Measured at Net Asset Value Per Share | Middle market | Unfunded Loan Commitment
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other long-term investments	18,712	29,783
Fair Value Measured at Net Asset Value Per Share | Global equity market
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other long-term investments	10,607	0
Fair Value Measured at Net Asset Value Per Share | Global equity market | Unfunded Loan Commitment
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other long-term investments	0	0
Fair Value Measured at Net Asset Value Per Share | Term liquidity facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other long-term investments	0	1,381
Fair Value Measured at Net Asset Value Per Share | Term liquidity facility | Unfunded Loan Commitment
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other long-term investments	0	0
Fair Value Measured at Net Asset Value Per Share | Late-stage growth
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other long-term investments	20,468	0
Fair Value Measured at Net Asset Value Per Share | Late-stage growth | Unfunded Loan Commitment
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other long-term investments	4,459	16,291
Fair Value Measured at Net Asset Value Per Share | Infrastructure
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other long-term investments	3,016	0
Fair Value Measured at Net Asset Value Per Share | Infrastructure | Unfunded Loan Commitment
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other long-term investments	$ 16,653	$ 17,497