BUSINESS SEGMENT INFORMATION - Geographic (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment information:
Total revenues	$ 225,310	$ 116,588	$ 596,677	$ 449,665
United States
Segment information:
Total revenues	217,711	110,823	572,170	421,323
International
Segment information:
Total revenues	$ 7,599	$ 5,765	$ 24,507	$ 28,342