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Debt And Liquidity (Narrative) (Details) - USD ($) |  |  |  | 3 Months Ended |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
Dec. 20, 2019 | Feb. 13, 2019 | Feb. 12, 2018 | Mar. 31, 2020 | Mar. 31, 2019 | Jun. 15, 2018 | Apr. 19, 2018 | Mar. 31, 2018
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Repayments of Long-term Debt |  |  |  | $ 0 | $ 125,000,000 |  |  |
Equity Interest Pledge |  |  | 65.00% |  |  |  |  |
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 | $ 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% |  |  |  |  |
Debt Instrument Prepayment Premium |  |  | 1.00% |  |  |  |  |
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 |  | $ 1,500,000,000
Borrowing Threshold |  |  | $ 35,000,000 |  |  |  |  |
Borrowing Threshold Percentage |  |  | 35.00% |  |  |  |  |
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 |  |  |  | $ 1,605,000,000 |  |  |  |

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