Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Current assets:
Cash and cash equivalents	$ 64,358	$ 66,459	$ 71,966
Receivables, net	920,824	836,605	890,579
Inventories	302,837	278,407	325,944
Current regulatory assets	60,557	63,613	80,661
Prepayments and other current assets	48,194	52,617	75,660
Total current assets	1,396,770	1,297,701	1,444,810
Noncurrent assets:
Property, plant and equipment	8,063,435	7,908,628	7,625,654
Less accumulated depreciation, depletion and amortization	3,064,833	2,991,486	2,903,274
Net property, plant and equipment	4,998,602	4,917,142	4,722,380
Goodwill	708,664	681,358	679,395
Other intangible assets, net	31,515	15,246	11,323
Regulatory assets	351,025	353,784	327,164
Investments	154,779	148,656	145,746
Operating lease right-of-use assets	115,751	115,323	118,795
Other	154,026	153,849	141,880
Total noncurrent assets	6,514,362	6,385,358	6,146,683
Total assets	7,911,132	7,683,059	7,591,493
Current liabilities:
Short-term borrowings	75,000	0	89,983
Long-term debt due within one year	16,560	16,540	51,822
Accounts payable	433,362	403,391	356,059
Taxes payable	80,882	48,970	46,731
Dividends payable	41,608	41,580	40,225
Accrued compensation	85,525	99,269	71,508
Regulatory liabilities due within one year	48,000	42,935	49,974
Operating lease liabilities due within one year	31,985	31,664	31,615
Asset retirement obligations due within one year	4,200	4,277	4,994
Other accrued liabilities	182,597	177,801	169,691
Total current liabilities	999,719	866,427	912,602
Noncurrent liabilities:
Long-term debt	2,265,316	2,226,567	2,327,984
Deferred income taxes	516,760	506,583	457,588
Regulatory liabilities	438,652	447,370	455,864
Asset retirement obligations	422,169	413,298	380,493
Operating lease liabilities	84,302	83,742	87,172
Other	286,527	291,826	309,489
Total noncurrent liabilities	4,013,726	3,969,386	4,018,590
Commitments and contingencies
Stockholders' equity:
Common stock	201,061	200,923	199,539
Other paid-in capital	1,363,182	1,355,404	1,315,511
Retained earnings	1,377,879	1,336,647	1,185,967
Accumulated other comprehensive loss	(40,809)	(42,102)	(37,090)
Treasury stock at cost - 538,921 shares	(3,626)	(3,626)	(3,626)
Total stockholders' equity	2,897,687	2,847,246	2,660,301
Total liabilities and stockholders' equity	$ 7,911,132	$ 7,683,059	$ 7,591,493
Common Stock, Shares Authorized	500,000,000	500,000,000	500,000,000
Common Stock, Par or Stated Value Per Share	$ 1.00	$ 1.00	$ 1.00
Common Stock, Shares, Issued	201,061,198	200,922,790	199,539,110
Treasury Stock, Common, Shares	538,921	538,921	538,921