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Accounts receivable and allowance for doubtful accounts Receivables and allowance for expected credit losses (Details 2) - USD ($) $ in Thousands | 3 Months Ended
--- | ---
Jun. 30, 2021 | Mar. 31, 2021 | Jun. 30, 2020 | Mar. 31, 2020
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |
Balance | $ 12,714 | $ 15,358 | $ 11,125 | $ 8,497
Current expected credit loss provision | (841) | (317) | 1,075 | 3,555
Less write-offs charged against the allowance | 1,424 | 2,669 | 1,399 | 1,265
Credit loss recoveries collected | 299 | 342 | 289 | 338
Balance | 10,748 | 12,714 | 11,090 | 11,125
Electric |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |
Balance | 678 | 899 | 492 | 328
Current expected credit loss provision | (110) | 538 | 303 | 555
Less write-offs charged against the allowance | 341 | 888 | 224 | 500
Credit loss recoveries collected | 100 | 129 | 88 | 109
Balance | 327 | 678 | 659 | 492
Natural gas distribution |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |
Balance | 2,950 | 2,571 | 1,817 | 1,056
Current expected credit loss provision | (103) | 1,273 | 190 | 1,156
Less write-offs charged against the allowance | 787 | 1,107 | 677 | 624
Credit loss recoveries collected | 199 | 213 | 201 | 229
Balance | 2,259 | 2,950 | 1,531 | 1,817
Pipeline |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |
Balance | 2 | 2 | 0 | 0
Current expected credit loss provision | 0 | 0 | 0 | 0
Less write-offs charged against the allowance | 0 | 0 | 0 | 0
Credit loss recoveries collected | 0 | 0 | 0 | 0
Balance | 2 | 2 | 0 | 0
Construction materials and contracting |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |
Balance | 4,842 | 6,164 | 5,983 | 5,357
Current expected credit loss provision | 11 | (1,049) | (314) | 694
Less write-offs charged against the allowance | 232 | 273 | 44 | 68
Credit loss recoveries collected | 0 | 0 | 0 | 0
Balance | 4,621 | 4,842 | 5,625 | 5,983
Construction services |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |
Balance | 4,242 | 5,722 | 2,833 | 1,756
Current expected credit loss provision | (639) | (1,079) | 896 | 1,150
Less write-offs charged against the allowance | 64 | 401 | 454 | 73
Credit loss recoveries collected | 0 | 0 | 0 | 0
Balance | $ 3,539 | $ 4,242 | $ 3,275 | $ 2,833

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- Definition Amount of allowance for credit loss on accounts receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5074-111524 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121599878&loc=SL82895884-210446 + Details
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- Definition Amount of increase in allowance for credit loss on accounts receivable, from recovery. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 + Details
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- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
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- Definition Amount of direct write-downs of accounts receivable charged against the allowance. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 + Details
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- Definition Amount of expense (reversal of expense) for expected credit loss on accounts receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(5)) -URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227 + Details
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