Summary of Significant Accounting Policies - Allowance for Credit Losses (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of year	$ 6,907
Impact of new accounting standard	695
Bad debt expense (benefit)	4,593	$ 784
Deductions for uncollectible receivables written off, net of recoveries	(809)
Credit allowance of acquired companies on the acquisition date	502
Purchase accounting adjustments	72
Reclass to other current liabilities	(315)
Balance at March 31, 2020	11,645
Service
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of year	3,192
Impact of new accounting standard	310
Bad debt expense (benefit)	2,384
Deductions for uncollectible receivables written off, net of recoveries	(728)
Balance at March 31, 2020	5,158
Construction
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of year	3,400
Impact of new accounting standard	331
Bad debt expense (benefit)	2,219
Deductions for uncollectible receivables written off, net of recoveries	(81)
Credit allowance of acquired companies on the acquisition date	502
Purchase accounting adjustments	72
Balance at March 31, 2020	6,443
Other.
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of year	315
Impact of new accounting standard	54
Bad debt expense (benefit)	(10)
Reclass to other current liabilities	(315)
Balance at March 31, 2020	$ 44