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Fair Value of Financial Instruments (Other Investments - Other Equity Method Investments) (Narrative) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Equity method investments, net investment	$ 242,000,000		$ 220,000,000
Loans Receivable [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Financing commitments			3,000,000
Confluence [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Equity method investments, ownership percentage	75.00%
Equity method investments, net investment	$ 400,000
Confluence [Member] \| Loans Receivable [Member] \| Maximum [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Financing commitments	2,500,000
Telecommunications Equity Method Investees [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Equity method investments, net investment	21,000,000		19,000,000
Equity method investments, equity contributions	2,000,000	$ 0
Receivables, related party	200,000
Payments for advance to affiliate	200,000
Telecommunications Equity Method Investees [Member] \| Subcontracting Arrangements [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Expenses, related party	1,800,000	$ 2,700,000
Payables, related party	300,000		200,000
Telecommunications Equity Method Investees [Member] \| Employee Leasing Arrangement
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Receivables, related party	$ 500,000		400,000
FM Tech [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Equity method investments, ownership percentage	50.00%
Equity method investments, net investment	$ 17,000,000		16,000,000
Equity method investments, equity contributions	2,000,000
FM Tech [Member] \| Equity Method Investments [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Financing commitments	$ 3,000,000		$ 9,000,000