Fair Value Measurement (Carrying Values And Fair Values Of The Company's Financial Instruments) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	$ 2,712,814	$ 2,819,263
Long-term Debt, Fair Value	2,790,750	2,863,355
Term-A Facility [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	1,137,123	1,245,175
Long-term Debt, Fair Value	1,147,000	1,254,855
5.00% Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	982,980	981,949
Long-term Debt, Fair Value	1,025,000	1,002,500
4.75% Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	592,711	592,139
Long-term Debt, Fair Value	$ 618,750	$ 606,000