Commitments And Contingencies - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Loss Contingencies [Line Items]
Notes payable, fair value disclosure	$ 571,000		$ 571,000
Interest rate swap principal	200,000		200,000		$ 200,000		$ 200,000
Proceeds from Sale of Debt Securities, Available-for-sale			12,840	$ 0
Debt Securities, Available-for-sale	10,000		10,000				10,000
Investments, fair value disclosure	10,000		10,000
Fair Value, Inputs, Level 2 [Member]
Loss Contingencies [Line Items]
Investments, fair value disclosure	10,000		10,000				10,000
Angola, Kwanza [Member]
Loss Contingencies [Line Items]
Foreign Currency Transaction Gain (Loss), before Tax	100	$ 2,000	(2,200)	(2,600)
Cash and cash equivalents	9,400		9,400				$ 6,200
Brazil, Brazil Real
Loss Contingencies [Line Items]
Foreign Currency Transaction Gain (Loss), before Tax	$ 700	$ 1,300	$ 8,400	$ 1,000
Senior Notes due 2024 [Member]
Loss Contingencies [Line Items]
Derivative Liability, Notional Amount						$ 100,000
Senior Notes due 2024 [Member] | London Interbank Offered Rate (LIBOR) [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Derivative, Variable Interest Rate						2.426%