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Debt And Liquidity (Refinancing) (Details) - USD ($) |  |  | 12 Months Ended |  |
--- | --- | --- | --- | --- | ---
Apr. 19, 2018 | Feb. 12, 2018 | Dec. 31, 2018 | Jun. 15, 2018 | Mar. 31, 2018
Debt Instrument [Line Items] |  |  |  |  |
Equity Interest Pledge |  | 65.00% |  |  |
Dividends Payable | $ 160,000,000 |  |  |  |
2018 Credit Agreement [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Ratio of Indebtedness to Net Capital |  | 4.00 |  |  |
Senior Notes [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt Instrument, Redemption Price, Percentage |  |  | 101.594% |  |
Line of Credit [Member] | 2018 Term Loan Facility [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Line of Credit Facility, Maximum Borrowing Capacity |  | $ 1,500,000,000 |  |  |
Debt Instrument, Amortization Rate |  | 5.00% |  |  |
Debt Instrument Prepayment Premium |  | 1.00% |  |  |
Excess Cashflow Threshold Percentage |  | 75.00% |  |  |
Line of Credit [Member] | 2018 Term Loan Facility [Member] | LIBO [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt Instrument, Basis Spread on Variable Rate |  | 3.50% |  |  |
Line of Credit [Member] | 2018 Term Loan Facility [Member] | ABR [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt Instrument, Basis Spread on Variable Rate |  | 2.50% |  |  |
Revolving Credit Facility [Member] | 2018 Revolving Credit Facility [Member] |  |  |  |  |
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% |  |  |
Revolving Credit Facility [Member] | 2018 Revolving Credit Facility [Member] | LIBO [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt Instrument, Basis Spread on Variable Rate |  | 3.75% |  |  |
Revolving Credit Facility [Member] | 2018 Revolving Credit Facility [Member] | ABR [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt Instrument, Basis Spread on Variable Rate |  | 2.75% |  |  |
Contingent Event One [Member] | Line of Credit [Member] | 2018 Term Loan Facility [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Excess Cashflow Threshold Percentage |  | 50.00% |  |  |
Contingent Event One [Member] | Line of Credit [Member] | 2018 Term Loan Facility [Member] | Minimum [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Ratio of Indebtedness to Net Capital |  | 1.25 |  |  |
Contingent Event One [Member] | Line of Credit [Member] | 2018 Term Loan Facility [Member] | Maximum |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Ratio of Indebtedness to Net Capital |  | 1.75 |  |  |
Contingent Event Two [Member] | Line of Credit [Member] | 2018 Term Loan Facility [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Excess Cashflow Threshold Percentage |  | 0.00% |  |  |
Brookfield [Member] | Brookfield Promissory Note [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Dividends Payable | $ 750,000,000 |  |  |  |
Brookfield [Member] | Brookfield Promissory Note [Member] | Maximum |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Supplementary Leverage Ratio | 175.00% |  |  |  |
Brookfield [Member] | Brookfield Promissory Note [Member] | LIBO [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt Instrument, Basis Spread on Variable Rate | 4.50% |  |  |  |
Third Anniversary [Member] | Brookfield [Member] | Brookfield Promissory Note [Member] | LIBO [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt Instrument, Basis Spread on Variable Rate | 2.00% |  |  |  |

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