Fair Value Measurements and Disclosures of Senior Notes (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 14,055
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	(14,055)
Derivative liability, gross	493,855
1.125% Convertible Senior Notes due 2021 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes Payable, Fair Value Disclosure	$ 198,200	$ 196,200
Senior Notes Percent of Par	99.10%	98.10%
6.125% Senior Notes due 2024 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes Payable, Fair Value Disclosure	$ 409,200	$ 410,800
Senior Notes Percent of Par	102.30%	102.70%
6.25% Senior Notes due 2025 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes Payable, Fair Value Disclosure	$ 105,900	$ 102,800
Senior Notes Percent of Par	103.50%	100.50%
5.75% Senior Notes due 2026 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes Payable, Fair Value Disclosure	$ 783,800	$ 775,500
Senior Notes Percent of Par	104.50%	103.40%