Condensed Consolidated Statements of Cash Flows - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
CASH FLOWS FROM (USED IN) OPERATING ACTIVITIES:
Net income	$ 32,328,000	$ 28,679,000
Adjustments to reconcile net income to net cash flow from (used in) operating activities:
Depreciation and amortization	19,152,000	16,138,000
Noncash lease expense	8,023,000	5,995,000
Stock-based compensation expense	3,443,000	2,635,000
Deferred income taxes	1,462,000	4,148,000
Change in allowance for bad debts	(999,000)	0
Loss on sale and retirement of property and equipment	15,000	22,000
Equity in losses of unconsolidated subsidiaries	1,000	1,000
Contract loss reserve	0	(372,000)
Change in assets and liabilities—net of effects from acquired businesses:
Receivables—net	(26,823,000)	(34,686,000)
Prepaid expenses	(3,960,000)	(7,620,000)
Taxes receivable—current	7,629,000	5,403,000
Other current assets	1,295,000	(102,000)
Employee supplemental savings plan asset	(358,000)	4,822,000
Other long-term assets	(2,051,000)	(997,000)
Accounts payable	(19,862,000)	27,450,000
Accrued salaries and related expenses	(3,015,000)	968,000
Operating lease obligations	(8,941,000)	(6,640,000)
Contract liabilities	(6,386,000)	8,926,000
Accrued expenses and other current liabilities	(4,963,000)	(4,014,000)
Accrued retirement	(3,750,000)	(8,089,000)
Other long-term liabilities	(66,000)	0
Other	(307,000)	(27,000)
Net cash flow from (used in) operating activities	(8,133,000)	42,640,000
CASH FLOWS FROM (USED IN) INVESTING ACTIVITIES:
Purchases of property and equipment	(17,854,000)	(25,370,000)
Investment in capitalized software	0	(4,402,000)
Net cash used in investing activities	(17,854,000)	(29,772,000)
CASH FLOWS FROM (USED IN) FINANCING ACTIVITIES:
Borrowing under revolving credit facility	131,000,000	231,500,000
Repayments under revolving credit facility	(124,500,000)	(153,000,000)
Dividends paid	(15,388,000)	(12,861,000)
Proceeds from exercise of stock options	3,142,000	2,055,000
Payment consideration to tax authority on employees' behalf	(2,489,000)	(777,000)
Principal paid on financing leases	(47,000)	(35,000)
Net cash flow from (used in) financing activities	(8,282,000)	66,882,000
NET CHANGE IN CASH AND CASH EQUIVALENTS	(34,269,000)	79,750,000
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	41,193,000	8,854,000
CASH AND CASH EQUIVALENTS, END OF PERIOD	6,924,000	88,604,000
SUPPLEMENTAL CASH FLOW INFORMATION
Cash paid for interest	327,000	639,000
Cash paid for income taxes, net of refunds	10,000	35,000
Noncash investing and financing activities:
Operating lease obligations arising from obtaining right of use assets	5,401,000	1,443,000
Finance lease obligations arising from obtaining right of use assets	62,000	0
Noncash investing activities	$ 479,000	$ 935,000