Segment financial information (Tables)

12 Months Ended

Dec. 31, 2017

Segment Reporting [Abstract]

Schedule of segment financial information

Segment financial information was as follows:

(in thousands)	Electric utility		Bank		Other			Total
2017
Revenues from external customers	$	2,257,455	$	297,640	$	530		$	2,555,625
Intersegment revenues (eliminations)	111		—		(111		)	—
Revenues	2,257,566		297,640		419			2,555,625
Depreciation and amortization	201,282		19,416		1,300			221,998
Interest expense, net	69,637		12,156		9,335			91,128
Income (loss) before income taxes	205,145		98,716		(27,281		)	276,580
Income taxes (benefit)	83,199		31,719		(5,525		)	109,393
Net income (loss)	121,946		66,997		(21,756		)	167,187
Preferred stock dividends of subsidiaries	1,995		—		(105		)	1,890
Net income (loss) for common stock	119,951		66,997		(21,651		)	165,297
Capital expenditures	441,598		53,272		317			495,187
Assets (at December 31, 2017)	6,196,281		6,798,659		104,888			13,099,828
2016
Revenues from external customers	$	2,094,224	$	285,924	$	506		$	2,380,654
Intersegment revenues (eliminations)	144		—		(144		)	—
Revenues	2,094,368		285,924		362			2,380,654
Depreciation and amortization	193,996		9,813		937			204,746
Interest expense, net	66,824		12,755		8,979			88,558
Income before income taxes	229,113		87,352		57,376			373,841
Income taxes	84,801		30,073		8,821			123,695
Net income	144,312		57,279		48,555			250,146
Preferred stock dividends of subsidiaries	1,995		—		(105		)	1,890
Net income for common stock	142,317		57,279		48,660			248,256
Capital expenditures	320,437		9,394		212			330,043
Assets (at December 31, 2016)	5,975,428		6,421,357		28,721			12,425,506
2015
Revenues from external customers	$	2,335,135	$	267,733	$	114		$	2,602,982
Intersegment revenues (eliminations)	31		—		(31		)	—
Revenues	2,335,166		267,733		83			2,602,982
Depreciation and amortization	186,319		7,928		1,338			195,585
Interest expense, net	66,370		11,326		10,780			88,476
Income (loss) before income taxes	217,131		83,812		(46,155		)	254,788
Income taxes (benefit)	79,422		29,082		(15,483		)	93,021
Net income (loss)	137,709		54,730		(30,672		)	161,767
Preferred stock dividends of subsidiaries	1,995		—		(105		)	1,890
Net income (loss) for common stock	135,714		54,730		(30,567		)	159,877
Capital expenditures	350,161		13,470		173			363,804
Assets (at December 31, 2015)	5,672,210		6,014,755		95,053			11,782,018