Equity and Debt Securities - Summary of Equity and Debt Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Cash and cash equivalents	$ 164,894	$ 87,426
Less: Cash equivalents	(77,067)	(47,461)
Equity and debt securities, Amortized Cost Basis	794,892	343,987
Equity and debt securities, Unrealized Gains	2,038	754
Equity and debt securities, Unrealized Losses	(4,313)	(298)
Equity and debt securities, Aggregate Fair Value	792,617	344,443
Debt Securities
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Debt securities, Amortized Cost Basis	660,404	173,104
Debt securities, Unrealized Gains	2,038	687
Debt securities, Unrealized Losses	(3,624)	(142)
Debt securities, Aggregate Fair Value	658,818	173,649
Short-Term Marketable Securities
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Debt securities, Amortized Cost Basis	152,029	41,061
Debt securities, Unrealized Gains	24	101
Debt securities, Unrealized Losses	(247)	(15)
Debt securities, Aggregate Fair Value	151,806	41,147
Short-Term Marketable Securities \| Money Market Accounts
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Cash and cash equivalents		47,461
Cash and cash equivalents fair value disclosure		47,461
Short-Term Marketable Securities \| Corporate Debt Securities
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Debt securities, Amortized Cost Basis	92,116	41,061
Debt securities, Unrealized Gains	24	101
Debt securities, Unrealized Losses	(148)	(15)
Debt securities, Aggregate Fair Value	91,992	41,147
Short-Term Marketable Securities \| US Government Debt Securities
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Debt securities, Amortized Cost Basis	51,318
Debt securities, Unrealized Losses	(81)
Debt securities, Aggregate Fair Value	51,237
Short-Term Marketable Securities \| Municipal Bonds
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Debt securities, Amortized Cost Basis	4,980
Debt securities, Unrealized Losses	(12)
Debt securities, Aggregate Fair Value	4,968
Short-Term Marketable Securities \| Yankee Debt Securities
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Debt securities, Amortized Cost Basis	3,615
Debt securities, Unrealized Losses	(6)
Debt securities, Aggregate Fair Value	3,609
Short-Term Equity Securities
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Marketable and non-marketable securities, Amortized Cost Basis	134,488	170,883
Marketable and non-marketable securities, Unrealized Gains		67
Marketable and non-marketable securities, Unrealized Losses	(689)	(156)
Marketable and non-marketable securities, Aggregate Fair Value	133,799	170,794
Short-Term Equity Securities \| Exchange Traded Funds
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Marketable and non-marketable securities, Amortized Cost Basis	35,174	17,614
Marketable and non-marketable securities, Unrealized Losses	(174)	(5)
Marketable and non-marketable securities, Aggregate Fair Value	35,000	17,609
Short-Term Equity Securities \| Money Market Accounts
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Cash and cash equivalents	77,067
Cash and cash equivalents fair value disclosure	77,067
Short-Term Equity Securities \| Bond Funds
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Marketable and non-marketable securities, Amortized Cost Basis	99,314	153,269
Marketable and non-marketable securities, Unrealized Gains		67
Marketable and non-marketable securities, Unrealized Losses	(515)	(151)
Marketable and non-marketable securities, Aggregate Fair Value	98,799	153,185
Equity Securities due After 1 Year through 5 Years
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Debt securities, Amortized Cost Basis	480,742	132,043
Debt securities, Unrealized Gains	49	586
Debt securities, Unrealized Losses	(3,334)	(127)
Debt securities, Aggregate Fair Value	477,457	132,502
Equity Securities due After 1 Year through 5 Years \| Corporate Debt Securities
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Debt securities, Amortized Cost Basis	242,421	124,989
Debt securities, Unrealized Gains	29	580
Debt securities, Unrealized Losses	(1,913)	(117)
Debt securities, Aggregate Fair Value	240,537	125,452
Equity Securities due After 1 Year through 5 Years \| US Government Debt Securities
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Debt securities, Amortized Cost Basis	147,699
Debt securities, Unrealized Gains	7
Debt securities, Unrealized Losses	(786)
Debt securities, Aggregate Fair Value	146,920
Equity Securities due After 1 Year through 5 Years \| Municipal Bonds
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Debt securities, Amortized Cost Basis	11,920
Debt securities, Unrealized Gains	13
Debt securities, Unrealized Losses	(11)
Debt securities, Aggregate Fair Value	11,922
Equity Securities due After 1 Year through 5 Years \| Yankee Debt Securities
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Debt securities, Amortized Cost Basis	8,633	6,054
Debt securities, Unrealized Gains		4
Debt securities, Unrealized Losses	(89)	(10)
Debt securities, Aggregate Fair Value	8,544	6,048
Equity Securities due After 1 Year through 5 Years \| Agency Securities
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Debt securities, Amortized Cost Basis	70,069	1,000
Debt securities, Unrealized Gains		2
Debt securities, Unrealized Losses	(535)
Debt securities, Aggregate Fair Value	69,534	$ 1,002
Equity Securities due After 5 Year through 10 Years
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Debt securities, Amortized Cost Basis	27,633
Debt securities, Unrealized Gains	1,965
Debt securities, Unrealized Losses	(43)
Debt securities, Aggregate Fair Value	29,555
Equity Securities due After 5 Year through 10 Years \| Municipal Bonds
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Debt securities, Amortized Cost Basis	7,633
Debt securities, Unrealized Losses	(43)
Debt securities, Aggregate Fair Value	7,590
Equity Securities due After 5 Year through 10 Years \| Redeemable Preferred Stock Investment
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Debt securities, Amortized Cost Basis	20,000
Debt securities, Unrealized Gains	1,965
Debt securities, Aggregate Fair Value	$ 21,965

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