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Debt And Liquidity (Narrative) (Details) - USD ($)			9 Months Ended
	Feb. 13, 2019	Feb. 12, 2018	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Jun. 15, 2018	Jun. 14, 2018	Apr. 19, 2018
Debt Instrument [Line Items]
Repayments of Long-term Debt			$ 249,214,000	$ 125,000,000
Debt Instrument, Repurchase Amount			80,000,000
Equity Interest Pledge		65.00%
2018 Term Loan Facility
Debt Instrument [Line Items]
Repayments of Long-term Debt	$ 350,000,000		$ 173,000,000
Debt Instrument, Redemption Price, Percentage			101.594%
2018 Credit Agreement
Debt Instrument [Line Items]
Ratio of Indebtedness to Net Capital		4.00
Line of Credit | 2018 Term Loan Facility
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 1,500,000,000					$ 1,500,000,000
Debt Instrument, Basis Spread on Variable Rate		0.25%
Debt Instrument, Amortization Rate		5.00%
Excess Cashflow Threshold Percentage		75.00%
Revolving Credit Facility | 2018 Revolving Credit Facility
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 250,000,000				$ 2,250,000,000
Debt Instrument, Basis Spread on Variable Rate		0.25%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage			0.25%
Borrowing Threshold		$ 35,000,000
Borrowing Threshold Percentage		35.00%
Line of credit upfront fee percentage						1.00%
LIBO | Line of Credit | 2018 Term Loan Facility
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		3.50%
LIBO | Revolving Credit Facility | 2018 Revolving Credit Facility
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		3.75%
ABR | Line of Credit | 2018 Term Loan Facility
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		2.50%
ABR | Revolving Credit Facility | 2018 Revolving Credit Facility
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		2.75%
Contingent Event One | Line of Credit | 2018 Term Loan Facility
Debt Instrument [Line Items]
Excess Cashflow Threshold Percentage		50.00%
Contingent Event Two | Line of Credit | 2018 Term Loan Facility
Debt Instrument [Line Items]
Excess Cashflow Threshold Percentage		0.00%
Minimum | Contingent Event One | Line of Credit | 2018 Term Loan Facility
Debt Instrument [Line Items]
Ratio of Indebtedness to Net Capital		1.25
Maximum | Contingent Event One | Line of Credit | 2018 Term Loan Facility
Debt Instrument [Line Items]
Ratio of Indebtedness to Net Capital		1.75
Brookfield | Brookfield Promissory Note
Debt Instrument [Line Items]
Dividends Payable								$ 750,000,000
Fair Value, Inputs, Level 3
Debt Instrument [Line Items]
Long-term Debt, Fair Value			$ 1,576,000,000		$ 1,813,000,000

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Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

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Carrying value as of the balance sheet date of dividends declared but unpaid on equity securities issued by the entity and outstanding.

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