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Debt And Liquidity (Narrative) (Details) - USD ($)					6 Months Ended
	Jun. 30, 2020	Dec. 20, 2019	Feb. 13, 2019	Feb. 12, 2018	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Jun. 30, 2018	Jun. 15, 2018	Apr. 19, 2018
Debt Instrument [Line Items]
Repayments of Long-term Debt					$ 100,028,000	$ 125,000,000
Equity Interest Pledge				65.00%
Debt Instrument, Repurchase Amount	$ 43,300,000				$ 43,300,000
Senior Notes
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage					101.594%
2018 Term Loan Facility | Senior Subordinated Notes
Debt Instrument [Line Items]
Repayments of Long-term Debt	60,000,000.0	$ 225,000,000	$ 125,000,000
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
Debt Instrument, Basis Spread on Variable Rate				0.25%
Debt Instrument, Amortization Rate				5.00%
Excess Cashflow Threshold Percentage				75.00%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage					25.00%
Revolving Credit Facility | 2018 Revolving Credit Facility
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity				$ 250,000,000				$ 1,500,000,000	$ 2,250,000,000
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	$ 1,689,000,000				$ 1,689,000,000		$ 1,813,000,000

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- Definition

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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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The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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Indebtedness divided by net capital.

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