Commitments And Contingencies - Narrative (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020 USD ($) derivative_instrument	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2019 USD ($)
Loss Contingencies [Line Items]
Notes payable, fair value disclosure	$ 325,000
Number of instruments held | derivative_instrument	2
Interest rate swap principal	$ 200,000			$ 200,000
Proceeds from Sale of Debt Securities, Available-for-sale	12,840		$ 70,000
Debt Securities, Available-for-sale	10,000			10,000
Fair Value, Inputs, Level 2 [Member]
Loss Contingencies [Line Items]
Investments, fair value disclosure	10,000			$ 10,000
Angola, Kwanza [Member]
Loss Contingencies [Line Items]
Foreign Currency Transaction Gain (Loss), before Tax	(1,900)	$ 100
Cash and cash equivalents	$ 6,200
Senior Notes due 2024 [Member]
Loss Contingencies [Line Items]
Fixed interest rate	4.65%
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%
Senior Notes due 2024 [Member] | London Interbank Offered Rate (LIBOR) [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Derivative, Variable Interest Rate	2.823%