Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 41,110	$ 12,485
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization expense	7,049	11,368
Bad debt expense	21,579	21,516
Compensation expense related to share-based awards	4,143	3,616
Deferred income taxes	11,174	10,282
Changes in operating assets and liabilities	(66,760)	(88,374)
Net cash provided by (used in) operating activities	18,295	(29,107)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of available-for-sale investments	(190,726)	(202,050)
Sales of available-for-sale investments	191,555	199,340
Purchases of property and equipment	(3,952)	(3,426)
Net cash used in investing activities	(3,123)	(6,136)
CASH FLOWS FROM FINANCING ACTIVITIES:
Issuance of common stock	1,608	2,548
Payments of employee tax associated with stock compensation	(3,313)	(1,170)
Net cash (used in) provided by financing activities	(1,705)	1,378
EFFECT OF FOREIGN CURRENCY EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS:		48
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	13,467	(33,817)
CASH AND CASH EQUIVALENTS, beginning of the period	18,899	50,882
CASH AND CASH EQUIVALENTS, end of the period	$ 32,366	$ 17,065