Other Investments - Allowance for Credit Loss (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Jan. 01, 2020	Dec. 31, 2019
Equity Securities Without Readily Determinable Fair Value, Allowance For Credit Loss [Roll Forward]
Balance at beginning of period	$ 0
Credit Loss	2,415
Deductions	0
Balance at end of period	2,415
New Accounting Pronouncement, Early Adoption [Line Items]
Accumulated earnings (losses)	$ 583,474		$ 632,809
Accounting Standards Update 2016-13
New Accounting Pronouncement, Early Adoption [Line Items]
Accumulated earnings (losses)		$ 2,900
Accounting Standards Update 2016-13 | Investments In And Advances To Affiliates, Subsidiaries, Associates, And Joint Ventures
New Accounting Pronouncement, Early Adoption [Line Items]
Accumulated earnings (losses)		$ 2,100