CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net income	$ 25,003	$ 22,396
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	64,255	54,707
Non-cash interest expense	614	578
Non-cash stock compensation expense	18,085	21,511
Non-cash income tax benefit	(100)	(1,520)
Non-cash amortization on investments	1,171	2,094
Changes in assets and liabilities, net of effects from acquisitions of businesses:
Accounts receivable, net	(179,350)	(21,859)
Pharmaceutical inventory	(9,388)	(1,188)
Other assets	(57,398)	(21,974)
Accounts payable and accrued liabilities	50,322	(59,372)
Medical claims payable and other medical liabilities	89,932	5,978
Contingent consideration	303	203
Tax contingencies	721	764
Deferred credits and other long-term liabilities	16,884	1,882
Other	69	(364)
Net cash provided by operating activities	21,123	3,836
Cash flows from investing activities:
Capital expenditures	(37,132)	(26,797)
Acquisitions and investments in businesses, net of cash acquired		(3,200)
Purchase of investments	(334,250)	(238,814)
Maturity of investments	227,446	233,143
Net cash used in investing activities	(143,936)	(35,668)
Cash flows from financing activities:
Proceeds from issuance of debt		200,000
Payments to acquire treasury stock	(14,323)	(5,000)
Proceeds from exercise of stock options	21,476	5,946
Payments on debt and capital lease obligations	(33,912)	(190,978)
Other	(3,051)	(1,311)
Net cash provided by (used in) financing activities	(29,810)	8,657
Net decrease in cash and cash equivalents	(152,623)	(23,175)
Cash and cash equivalents at beginning of period	398,732	304,508
Cash and cash equivalents at end of period	246,109	281,333
Non-cash investing activities:
Property and equipment acquired under capital leases	$ 4,623	$ 2,418