Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 42,466	$ 41,110
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	6,752	7,049
Bad debt expense	32,028	21,579
Compensation expense related to share-based awards	3,922	4,143
Deferred income taxes	16,265	11,174
Changes in operating assets and liabilities	(16,042)	(66,760)
Net cash provided by operating activities	85,391	18,295
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of available-for-sale investments	(418,156)	(190,726)
Sales of available-for-sale investments	382,022	191,555
Purchases of property and equipment	(3,220)	(3,952)
Other	9
Net cash used in investing activities	(39,345)	(3,123)
CASH FLOWS FROM FINANCING ACTIVITIES:
Issuance of common stock	1,326	1,608
Payments of employee tax associated with stock compensation	(2,692)	(3,313)
Net cash used in financing activities	(1,366)	(1,705)
NET INCREASE IN CASH AND CASH EQUIVALENTS	44,680	13,467
CASH AND CASH EQUIVALENTS, beginning of the period	32,731	18,899
CASH AND CASH EQUIVALENTS, end of the period	$ 77,411	$ 32,366