Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 24,232	$ 26,253
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	4,468	4,685
Bad debt expense	23,141	13,679
Compensation expense related to share-based awards	2,406	2,698
Deferred income taxes	9,213	6,641
Changes in operating assets and liabilities	(10,046)	(39,202)
Net cash provided by operating activities	53,414	14,754
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of available-for-sale investments	(296,666)	(101,043)
Sales of available-for-sale investments	265,743	106,139
Purchases of property and equipment	(1,408)	(2,737)
Other	9
Net cash (used in) provided by investing activities	(32,322)	2,359
CASH FLOWS FROM FINANCING ACTIVITIES:
Issuance of common stock	180	1,170
Payments of employee tax associated with stock compensation	(2,562)	(3,218)
Net cash used in financing activities	(2,382)	(2,048)
NET INCREASE IN CASH AND CASH EQUIVALENTS	18,710	15,065
CASH AND CASH EQUIVALENTS, beginning of the period	32,731	18,899
CASH AND CASH EQUIVALENTS, end of the period	$ 51,441	$ 33,964