Condensed Unaudited Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities:
Net income	$ 163,330	$ 106,864
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	118,975	101,615
Non-cash interest expense, net	737	1,451
Non-cash stock-based compensation expense	7,940	6,571
Benefit from deferred income taxes	(14,190)	(172)
Equity in earnings of unconsolidated affiliates	(12,811)	(11,409)
Gains on sales of assets, net, including fixed assets held-for-sale	(6,074)	(6,920)
Other non-cash items, net	(2,899)	2,686
Changes in assets and liabilities, net of acquisitions:
Accounts receivable, net	117,023	(471,716)
Inventories	(265)	(8,550)
Other assets, current and long-term portion	6,187	58,949
Accounts payable and accrued expenses	(26,355)	188,511
Billings in excess of costs and earnings	(28,406)	44,524
Other liabilities, current and long-term portion	28,269	10,813
Net cash provided by operating activities	351,461	23,217
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	(94,647)	(6,684)
Capital expenditures	(57,455)	(87,997)
Proceeds from sale of property and equipment	19,567	13,884
Payments for other investments	(4,972)	(35,713)
Proceeds from other investments	14,705	5,415
Net cash used in investing activities	(122,802)	(111,095)
Cash flows from financing activities:
Proceeds from credit facilities	1,627,909	1,638,874
Repayments of credit facilities	(1,754,043)	(1,374,552)
Proceeds from (repayments of) other borrowings, net	1	(15,800)
Payments of finance lease obligations	(38,646)	(37,926)
Payments of acquisition-related contingent consideration	29,267	15,929
Proceeds from (distributions to) non-controlling interests	584	(559)
Proceeds from stock-based awards, net	2,289	1,927
Repurchases of common stock	(5,652)	(128,311)
Net cash (used in) provided by financing activities	(196,825)	67,724
Effect of currency translation on cash	(80)	512
Net increase (decrease) in cash and cash equivalents	31,754	(19,642)
Cash and cash equivalents - beginning of period	27,422	40,326
Cash and cash equivalents - end of period	59,176	20,684
Supplemental cash flow information:
Interest paid	43,102	36,068
Income tax payments (refunds), net	39,417	(13,975)
Supplemental disclosure of non-cash information:
Additions to property and equipment from finance leases	$ 110,164	$ 39,548