CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
CONSOLIDATED BALANCE SHEETS
Accounts receivable, allowance for doubtful accounts (in dollars)		$ 6,907
Billed accounts receivable, allowance for credit losses (in dollars)	$ 9,998
Unbilled accounts receivable, allowance for credit losses (in dollars)	684	0
Other receivables, allowance for credit losses (In dollars)	884	0
Costs and estimated earnings in excess of billings, allowance for credit losses	$ 79	$ 0
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	102,969,912	102,969,912
Common stock, shares issued	41,123,365	41,123,365
Treasury stock, shares	4,620,071	4,465,448