Long-Term Debt - Senior Unsecured Notes (Details) - USD ($) $ in Thousands	1 Months Ended		12 Months Ended
	Oct. 31, 2017	Sep. 30, 2017	Dec. 31, 2019	Dec. 31, 2018
Long Term Debt
Long-term Debt, Gross			$ 2,764,472	$ 2,401,393
Outstanding Balance			2,734,344	2,376,723
5 1/4% Senior Notes due 2023
Long Term Debt
Long-term Debt, Gross			$ 400,000	400,000
Stated interest rate			5.25%
5 1/4% Senior Notes due 2023 | Debt Instrument, Redemption, Period One [Member]
Long Term Debt
Redemption price of debt instrument (as a percent)			101.75%
5 1/4% Senior Notes due 2023 | Debt Instrument, Redemption, Period Two [Member]
Long Term Debt
Redemption price of debt instrument (as a percent)			100.875%
5 1/4% Senior Notes due 2023 | Debt Instrument, Redemption, Period Three [Member]
Long Term Debt
Redemption price of debt instrument (as a percent)			100.00%
2.800% senior notes due 2024
Long Term Debt
Long-term Debt, Gross			$ 400,000
Stated interest rate			2.80%
Redemption price of debt instrument (as a percent)			100.00%
5.500% senior notes due 2024
Long Term Debt
Long-term Debt, Gross			$ 500,000	500,000
Stated interest rate			5.50%
5.500% senior notes due 2024 | Debt Instrument, Redemption, Period One [Member]
Long Term Debt
Redemption price of debt instrument (as a percent)			102.75%
5.500% senior notes due 2024 | Debt Instrument, Redemption, Period Two [Member]
Long Term Debt
Redemption price of debt instrument (as a percent)			101.833%
5.500% senior notes due 2024 | Debt Instrument, Redemption, Period Three [Member]
Long Term Debt
Redemption price of debt instrument (as a percent)			100.917%
5.500% senior notes due 2024 | Debt Instrument, Redemption, Period Four [Member]
Long Term Debt
Redemption price of debt instrument (as a percent)			100.00%
4.125% senior notes due 2025
Long Term Debt
Long-term Debt, Gross			$ 350,000	350,000
Stated interest rate		4.125%	4.125%
4.125% senior notes due 2025 | Maximum
Long Term Debt
Maximum redemption of debt instrument (as a percent)			35.00%
4.125% senior notes due 2025 | Debt Instrument, Redemption, Period One [Member]
Long Term Debt
Redemption price of debt instrument (as a percent)			104.125%
4.125% senior notes due 2025 | Debt Instrument, Redemption, Period Two [Member]
Long Term Debt
Redemption price of debt instrument (as a percent)			102.063%
4.125% senior notes due 2025 | Debt Instrument, Redemption, Period Three [Member]
Long Term Debt
Redemption price of debt instrument (as a percent)			101.031%
4.125% senior notes due 2025 | Debt Instrument, Redemption, Period Four [Member]
Long Term Debt
Redemption price of debt instrument (as a percent)			100.00%
5.000% senior notes due 2026
Long Term Debt
Long-term Debt, Gross			$ 400,000	400,000
Stated interest rate			5.00%
5.000% senior notes due 2026 | Maximum
Long Term Debt
Maximum redemption of debt instrument (as a percent)			35.00%
5.000% senior notes due 2026 | Debt Instrument, Redemption, Period One [Member]
Long Term Debt
Redemption price of debt instrument (as a percent)			105.00%
5.000% senior notes due 2026 | Debt Instrument, Redemption, Period Two [Member]
Long Term Debt
Redemption price of debt instrument (as a percent)			102.50%
5.000% senior notes due 2026 | Debt Instrument, Redemption, Period Three [Member]
Long Term Debt
Redemption price of debt instrument (as a percent)			101.667%
5.000% senior notes due 2026 | Debt Instrument, Redemption, Period Four [Member]
Long Term Debt
Redemption price of debt instrument (as a percent)			100.833%
5.000% senior notes due 2026 | Debt Instrument, Redemption, Period Five [Member]
Long Term Debt
Redemption price of debt instrument (as a percent)			100.00%
3.450% senior notes due 2030
Long Term Debt
Long-term Debt, Gross			$ 600,000
Stated interest rate			3.45%
Redemption price of debt instrument (as a percent)			100.00%
5.125% senior notes due 2021
Long Term Debt
Long-term Debt, Gross				$ 700,000
Stated interest rate			5.125%
Redemption price of debt instrument (as a percent)			100.00%
6.375% senior notes due 2022
Long Term Debt
Stated interest rate			6.375%
Redemption price of debt instrument (as a percent)	103.188%	103.563%
US Treasury (UST) Interest Rate [Member] | 2.800% senior notes due 2024
Long Term Debt
Debt Instrument, Basis Spread on Variable Rate			0.20%
US Treasury (UST) Interest Rate [Member] | 4.125% senior notes due 2025
Long Term Debt
Debt Instrument, Basis Spread on Variable Rate			0.50%
US Treasury (UST) Interest Rate [Member] | 5.000% senior notes due 2026
Long Term Debt
Debt Instrument, Basis Spread on Variable Rate			0.50%
US Treasury (UST) Interest Rate [Member] | 3.450% senior notes due 2030
Long Term Debt
Debt Instrument, Basis Spread on Variable Rate			0.25%