CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities:
Net income	$ 52,148	$ 55,632
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	97,302	82,896
Non-cash interest expense	919	3,120
Non-cash stock compensation expense	27,405	31,834
Non-cash income tax (benefit) provision	1,814	(2,160)
Non-cash amortization on investments	1,404	3,052
Changes in assets and liabilities, net of effects from acquisitions of businesses:
Accounts receivable, net	(160,904)	(13,539)
Pharmaceutical inventory	(3,090)	9,609
Other assets	(60,008)	(15,481)
Accounts payable and accrued liabilities	(13,781)	(70,006)
Medical claims payable and other medical liabilities	73,667	25,578
Contingent consideration	451	(631)
Tax contingencies	100	158
Deferred credits and other long-term liabilities	16,497	2,408
Other	93	210
Net cash provided by operating activities	34,017	112,680
Cash flows from investing activities:
Capital expenditures	(51,244)	(42,703)
Acquisitions and investments in businesses, net of cash acquired	(402)	(3,200)
Purchases of investments	(453,007)	(341,280)
Proceeds from maturities and sales of investments	400,683	320,045
Net cash used in investing activities	(103,970)	(67,138)
Cash flows from financing activities:
Proceeds from issuance of debt		949,239
Payments to acquire treasury stock	(41,039)	(15,457)
Proceeds from exercise of stock options	22,587	28,328
Payments on debt, capital lease and deferred financing obligations	(75,043)	(798,359)
Payments on contingent consideration		(1,032)
Other	(1,020)	(8,005)
Net cash provided by (used in) financing activities	(94,515)	154,714
Net increase (decrease) in cash and cash equivalents	(164,468)	200,256
Cash and cash equivalents at beginning of period	398,732	304,508
Cash and cash equivalents at end of period	234,264	504,764
Non-cash investing activities:
Assets acquired under capital leases and deferred financing	$ 19,545	$ 2,418