Fair Value Measurement (Carrying Values and Fair Values of the Company's Financial Instruments) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt	$ 2,834,664	$ 2,849,307
Carrying Amount | Term Loan A Facility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt	663,245	669,878
Carrying Amount | 5.00% Notes due April 2024
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt	397,210	991,074
Carrying Amount | 4.75% Notes due December 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt		398,230
Carrying Amount | 4.25% Notes due February 2029
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt	983,112
Carrying Amount | 4.75% Notes due August 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt	791,097	790,125
Estimated Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt	2,901,688	2,907,379
Estimated Fair Value | Term Loan A Facility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt	669,938	665,719
Estimated Fair Value | 5.00% Notes due April 2024
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt	404,500	1,015,000
Estimated Fair Value | 4.75% Notes due December 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt		400,500
Estimated Fair Value | 4.25% Notes due February 2029
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt	1,006,250
Estimated Fair Value | 4.75% Notes due August 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt	$ 821,000	$ 826,160