Selected Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands |
3 Months Ended | 12 Months Ended | |||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Sep. 30, 2018 |
Jun. 30, 2018 |
Mar. 31, 2018 |
Dec. 31, 2017 |
Sep. 30, 2017 |
Jun. 30, 2017 |
Mar. 31, 2017 |
Dec. 31, 2016 |
Sep. 30, 2018 |
Sep. 30, 2017 |
Sep. 30, 2016 |
|
Operating Revenues by Segment [Line Items] | |||||||||||
Operating revenues | $ 444,700 | $ 562,245 | $ 1,219,409 | $ 889,192 | $ 464,880 | $ 526,501 | $ 988,186 | $ 780,168 | |||
Operating income | 89,592 | 122,993 | 268,988 | 241,561 | 91,792 | 140,664 | 285,172 | 209,918 | $ 723,134 | $ 727,546 | $ 657,230 |
Income from continuing operations | 35,853 | 70,808 | 162,012 | 114,038 | 603,064 | 382,711 | 345,542 | ||||
Income from discontinued operations, net of tax, before gain on disposal | 0 | 0 | 0 | 10,994 | |||||||
Gain on sale of discontinued operations, net of tax ($0, $10,215 and $0) | 0 | 0 | 2,716 | 0 | 0 | 2,716 | 0 | ||||
Net income | $ 38,747 | $ 71,193 | $ 178,992 | $ 314,132 | $ 35,853 | $ 70,808 | $ 164,728 | $ 125,032 | $ 603,064 | $ 396,421 | $ 350,104 |
Basic and diluted earnings per share | |||||||||||
Net income per share - basic and diluted (in dollars per share) | $ 0.35 | $ 0.64 | $ 1.60 | $ 2.89 | $ 0.34 | $ 0.67 | $ 1.55 | $ 1.19 | $ 5.43 | $ 3.73 | $ 3.38 |
Income per share from continuing operations (in dollars per share) | 0.34 | 0.67 | 1.52 | 1.08 | 5.43 | 3.60 | 3.33 | ||||
Income per share from discontinued operations (in dollars per share) | $ 0.00 | $ 0.00 | $ 0.03 | $ 0.11 | $ 0.00 | $ 0.13 | $ 0.05 | ||||
Distribution | |||||||||||
Operating Revenues by Segment [Line Items] | |||||||||||
Operating revenues | $ 407,476 | $ 535,488 | $ 1,199,291 | $ 860,792 | $ 437,918 | $ 494,060 | $ 962,541 | $ 754,656 | |||
Pipeline and Storage | |||||||||||
Operating Revenues by Segment [Line Items] | |||||||||||
Operating revenues | 132,662 | 127,633 | 120,955 | 126,463 | 117,823 | 117,283 | 111,972 | 109,952 | |||
Eliminations | |||||||||||
Operating Revenues by Segment [Line Items] | |||||||||||
Operating revenues | (95,438) | (100,876) | (100,837) | (98,063) | (90,861) | (84,842) | (86,327) | (84,440) | |||
Natural Gas, US Regulated | |||||||||||
Operating Revenues by Segment [Line Items] | |||||||||||
Total purchased gas cost | $ 43,085 | $ 130,886 | $ 626,960 | $ 366,917 | $ 72,561 | $ 114,176 | $ 427,494 | $ 311,305 | $ 1,167,848 | $ 925,536 | $ 746,192 |