Fair Value Measurements - Narrative (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Feb. 04, 2020	Dec. 31, 2019
6% Senior notes
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			6.00%
Five Percent Senior Notes Due Two Thousand Twenty Eight [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		5.00%	5.00%
Carrying Value | 6% Senior notes | Fair value inputs, Level 2
Debt Instrument [Line Items]
Financial Liabilities Fair Value Disclosure	$ 0		$ 496,531
Carrying Value | Five Percent Senior Notes Due Two Thousand Twenty Eight [Member] | Fair value inputs, Level 2
Debt Instrument [Line Items]
Financial Liabilities Fair Value Disclosure	491,874		0
Fair Value | 6% Senior notes | Fair value inputs, Level 2
Debt Instrument [Line Items]
Financial Liabilities Fair Value Disclosure	0		522,045
Fair Value | Five Percent Senior Notes Due Two Thousand Twenty Eight [Member] | Fair value inputs, Level 2
Debt Instrument [Line Items]
Financial Liabilities Fair Value Disclosure	$ 490,155		$ 0