CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities:
Net income	$ 29,228	$ 20,760
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	39,231	43,392
Stock-based compensation expense	1,202	858
Gain on sale of property and equipment	(7,332)	(4,713)
Unrealized loss on interest rate swap	4,907	4,194
Other non-cash items	2,823	160
Changes in assets and liabilities:
Accounts receivable	(65,860)	(97,964)
Contract assets	(32,765)	(51,048)
Other current assets	(3,268)	5,309
Other long-term assets	223	(137)
Accounts payable	21,897	(31,405)
Contract liabilities	30,784	4,205
Operating lease assets and liabilities, net	(551)	(918)
Accrued liabilities	22,125	13,481
Other long-term liabilities	18,007	(2,698)
Net cash provided by (used in) operating activities	60,651	(96,524)
Cash flows from investing activities:
Purchase of property and equipment	(21,703)	(56,907)
Proceeds from sale of property and equipment	12,086	21,196
Net cash used in investing activities	(9,617)	(35,711)
Cash flows from financing activities:
Borrowings under revolving line of credit		140,000
Payments on revolving line of credit		(85,000)
Proceeds from issuance of long-term debt	33,873	23,105
Repayment of long-term debt	(32,469)	(34,320)
Proceeds from issuance of common stock purchased under a long-term incentive plan	578	1,804
Payment of taxes on conversion of Restricted Stock Units	(77)	(1,519)
Cash distribution to noncontrolling interest holders	(1,000)	(3,505)
Repurchase of common stock	(8,343)
Dividends paid	(5,814)	(6,094)
Other	(2,014)	(39)
Net cash (used in) provided by financing activities	(15,266)	34,432
Effect of exchange rate changes on cash and cash equivalents	(384)	854
Net change in cash and cash equivalents	35,384	(96,949)
Cash and cash equivalents at beginning of the year	120,286	151,063
Cash and cash equivalents at end of the year	155,670	54,114
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Cash paid for interest	7,735	7,955
Cash paid for income taxes, net of refunds received	(13)	(9,599)
Leased assets obtained in exchange for new operating leases	42,450	51,060
SUPPLEMENTAL DISCLOSURES OF NONCASH INVESTING AND FINANCING ACTIVITIES
Dividends declared and not yet paid	$ 2,893	$ 3,058