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Debt And Liquidity (Narrative) (Details) - USD ($)				9 Months Ended
Debt And Liquidity (Narrative) (Details) - USD ($)	Feb. 13, 2019	Apr. 19, 2018	Feb. 12, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Jun. 15, 2018	Mar. 31, 2018	Dec. 31, 2017	Nov. 20, 2012
Debt Instrument [Line Items]
Repayments of Long-term Debt				$ 125,000,000	$ 28,125,000
Long-term Debt				2,036,362,000		$ 2,156,634,000
Stated interest rate									6.375%
Loan balance, net of unamortized discount				$ 70,861,000		106,323,000
Equity interest pledge				65.00%
Senior Subordinated Notes
Debt Instrument [Line Items]
Long-term Debt				$ 2,035,624,000		$ 2,155,883,000
Senior Notes
Debt Instrument [Line Items]
Principal amount issued										$ 300,000,000
Stated interest rate										6.375%
Debt Instrument, Redemption Price, Percentage					101.594%
2018 Term Loan Facility \| Senior Subordinated Notes
Debt Instrument [Line Items]
Repayments of Long-term Debt	$ 125,000,000
2018 Credit Agreement
Debt Instrument [Line Items]
Leverage ratio				4.00
Revolving Credit Facility \| Amended and Restated Credit Agreement July 2015
Debt Instrument [Line Items]
Long-term Line of Credit									$ 39,500,000
Outstanding letters of credit									8,700,000
Revolving Credit Facility \| 2018 Revolving Credit Facility
Debt Instrument [Line Items]
Borrowing capacity			$ 250,000,000				$ 2,250,000,000	$ 1,500,000,000
Borrowing threshold (greater than)				$ 35,000,000
Borrowing threshold percentage				35.00%
Increase in borrowing capacity							$ 750,000,000
Debt instrument, upfront fees							1.00%
Revolving Credit Facility \| 2018 Revolving Credit Facility \| LIBO
Debt Instrument [Line Items]
Margin spread on variable interest rate			3.75%
Revolving Credit Facility \| 2018 Revolving Credit Facility \| ABR
Debt Instrument [Line Items]
Margin spread on variable interest rate			2.75%
Term Loan Facility \| Amended and Restated Credit Agreement July 2015
Debt Instrument [Line Items]
Long-term Line of Credit									$ 18,700,000
Line of Credit \| 2018 Term Loan Facility
Debt Instrument [Line Items]
Borrowing capacity			$ 1,500,000,000
Margin spread on variable interest rate				0.25%
Debt Instrument, Amortization Rate				5.00%
Prepayment premium				1.00%
Excess Cashflow Threshold Percentage				75.00%
Line of Credit \| 2018 Term Loan Facility \| Contingent Event One
Debt Instrument [Line Items]
Excess Cashflow Threshold Percentage				50.00%
Line of Credit \| 2018 Term Loan Facility \| Contingent Event Two
Debt Instrument [Line Items]
Excess Cashflow Threshold Percentage				0.00%
Leverage ratio				1.25
Line of Credit \| 2018 Term Loan Facility \| Minimum \| Contingent Event One
Debt Instrument [Line Items]
Leverage ratio				1.25
Line of Credit \| 2018 Term Loan Facility \| Maximum \| Contingent Event One
Debt Instrument [Line Items]
Leverage ratio				1.75
Line of Credit \| 2018 Term Loan Facility \| LIBO
Debt Instrument [Line Items]
Margin spread on variable interest rate			3.50%
Undrawn commitment fee			0.25%
Line of Credit \| 2018 Term Loan Facility \| ABR
Debt Instrument [Line Items]
Margin spread on variable interest rate			2.50%
Brookfield \| Brookfield Promissory Note [Member]
Debt Instrument [Line Items]
Dividends Payable		$ 750,000,000
Brookfield \| Brookfield Promissory Note [Member] \| Maximum
Debt Instrument [Line Items]
Leverage ratio		175.00%
Brookfield \| Brookfield Promissory Note [Member] \| LIBO
Debt Instrument [Line Items]
Margin spread on variable interest rate		4.50%
Third Anniversary \| Brookfield \| Brookfield Promissory Note [Member] \| LIBO
Debt Instrument [Line Items]
Margin spread on variable interest rate		2.00%