Investment Information - Investment in operating affiliates (Details) € / shares in Units, € in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2021 EUR (€)	Jun. 30, 2020 USD ($)	Jun. 30, 2021 € / shares	Dec. 31, 2020 USD ($)
Schedule of Equity Method Investments [Line Items]
Payments to Acquire Interest in Subsidiaries and Affiliates			$ 546,349		$ 0
Investment in operating affiliates	$ 731,810		731,810				$ 129,291
Income (loss) from operating affiliates	$ 24,476	$ (3,173)	$ 99,933		$ 5,343
Operating Affiliates
Schedule of Equity Method Investments [Line Items]
Time lag for reporting			3 months	3 months
Coface
Schedule of Equity Method Investments [Line Items]
Percentage ownership	29.50%		29.50%
Consideration paid per share | € / shares						€ 9.95
Payments to Acquire Interest in Subsidiaries and Affiliates			$ 546,000	€ 453,000
Investment in operating affiliates	$ 601,900		601,900
Income (loss) from operating affiliates			74,500
Purchase Of Affiliate, Deferred Gain	$ 36,000		$ 36,000
Purchase Of Operating Affiliate, Deferred Gain, Period Of Recognition			5 years	5 years