Fair Value - Rollforward of Level 3 assets and liabilities (Details) - Recurring - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Contingent consideration liability
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period		$ (461)	$ (7,998)
Total gains or (losses) (realized/unrealized) - included in earnings	[1]	0	(54)
Total gains or (losses) (realized/unrealized) - included in other comprehensive income		0	0
Purchases, issuances, sales and settlements
Purchases		0	0
Issuances		0	0
Sales		0	0
Settlements		(4)	85
Transfers in and/or out of Level 3		0	0
Balance at end of period		(465)	(7,967)
Available for sale | Structured securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	[2]	3,426	5,216
Total gains or (losses) (realized/unrealized) - included in earnings	[1],[2]	(68)	9
Total gains or (losses) (realized/unrealized) - included in other comprehensive income	[2]	114	(22)
Purchases, issuances, sales and settlements
Purchases	[2]	0	0
Issuances	[2]	0	0
Sales	[2]	0	0
Settlements	[2]	0	(1,357)
Transfers in and/or out of Level 3	[2]	0	0
Balance at end of period	[2]	3,472	3,846
Available for sale | Corporate bonds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period		13	8,851
Total gains or (losses) (realized/unrealized) - included in earnings	[1]	0	7
Total gains or (losses) (realized/unrealized) - included in other comprehensive income		0	(5,416)
Purchases, issuances, sales and settlements
Purchases		0	0
Issuances		0	0
Sales		0	0
Settlements		0	(1,462)
Transfers in and/or out of Level 3		0	0
Balance at end of period		13	1,980
Fair value option | Corporate bonds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period		985	932
Total gains or (losses) (realized/unrealized) - included in earnings	[1]	4	0
Total gains or (losses) (realized/unrealized) - included in other comprehensive income		0	0
Purchases, issuances, sales and settlements
Purchases		0	33
Issuances		0	0
Sales		0	0
Settlements		0	0
Transfers in and/or out of Level 3		0	0
Balance at end of period		989	965
Fair value option | Other investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period		67,103	68,817
Total gains or (losses) (realized/unrealized) - included in earnings	[1]	248	(27)
Total gains or (losses) (realized/unrealized) - included in other comprehensive income		0	0
Purchases, issuances, sales and settlements
Purchases		7,365	21
Issuances		0	0
Sales		(6,786)	(17,175)
Settlements		0	0
Transfers in and/or out of Level 3		0	2,984
Balance at end of period		67,930	54,620
Fair value option | Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period		68,988	58,094
Total gains or (losses) (realized/unrealized) - included in earnings	[1]	2,188	1,921
Total gains or (losses) (realized/unrealized) - included in other comprehensive income		0	0
Purchases, issuances, sales and settlements
Purchases		0	0
Issuances		0	0
Sales		0	0
Settlements		0	0
Transfers in and/or out of Level 3		0	0
Balance at end of period		71,176	60,015
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period		42,015	55,889
Total gains or (losses) (realized/unrealized) - included in earnings	[1]	904	(3,721)
Total gains or (losses) (realized/unrealized) - included in other comprehensive income		0	0
Purchases, issuances, sales and settlements
Purchases		193	3,464
Issuances		0	0
Sales		0	0
Settlements		0	0
Transfers in and/or out of Level 3		0	0
Balance at end of period		$ 43,112	$ 55,632

[1] Gains or losses were included in net realized gains (losses).

[2] Includes asset backed securities, mortgage backed securities and commercial mortgage backed securities.