Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Balance at beginning of period	$ 353,667	$ 653,046	$ 1,627,136
Change in accumulated other comprehensive income	4,890	0	0
Balance at end of period	397,340	353,667	653,046
Accumulated Other Comprehensive Income [Member]
Balance at beginning of period	0	0	0
Change in accumulated other comprehensive income	4,890	0
Balance at end of period	4,890	0	0
Foreign Currency [Member]
Balance at beginning of period	0	0
Change in accumulated other comprehensive income	4,890	0
Balance at end of period	$ 4,890	$ 0	$ 0