Consolidated Statements of Cash Flows (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities
Net income	$ 46,400,000	$ 34,152,000
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation of property, plant and equipment	43,181,000	39,726,000
Other amortization	1,609,000	935,000
Provision for loan losses	995,000	1,858,000
Loans receivable originated and purchased, held for sale	(46,998,000)	(79,224,000)
Proceeds from sale of loans receivable, held for sale	48,720,000	102,254,000
Increase in deferred income taxes	6,298,000	19,967,000
Excess tax benefits from share-based payment arrangements	(164,000)	(414,000)
Allowance for equity funds used during construction	(1,609,000)	(1,215,000)
Change in cash overdraft	(1,038,000)	0
Changes in assets and liabilities
Decrease in accounts receivable and unbilled revenues, net	22,352,000	14,335,000
Increase in fuel oil stock	(34,260,000)	(29,272,000)
Increase in regulatory assets	(9,258,000)	(17,746,000)
Increase (decrease) in accounts, interest and dividends payable	(9,307,000)	38,148,000
Change in prepaid and accrued income taxes and utility revenue taxes	(19,474,000)	(50,933,000)
Decrease in defined benefit pension and other postretirement benefit plans liability	(818,000)	(702,000)
Change in other assets and liabilities	(27,208,000)	(23,550,000)
Net cash provided by operating activities	19,421,000	48,319,000
Cash flows from investing activities
Available-for-sale investment and mortgage-related securities purchased	(79,912,000)	(26,705,000)
Principal repayments on available-for-sale investment and mortgage-related securities	15,597,000	36,504,000
Proceeds from sale of available-for-sale investment securities	79,564,000	0
Net increase in loans held for investment	(37,887,000)	(66,934,000)
Proceeds from sale of real estate acquired in settlement of loans	1,429,000	3,046,000
Capital expenditures	(65,829,000)	(71,041,000)
Contributions in aid of construction	6,958,000	11,710,000
Other	5,848,000	869,000
Net cash used in investing activities	(74,232,000)	(112,551,000)
Cash flows from financing activities
Net increase in deposit liabilities	105,510,000	82,704,000
Net increase in short-term borrowings with original maturities of three months or less	30,887,000	50,244,000
Net increase (decrease) in retail repurchase agreements	141,000	(2,680,000)
Proceeds from issuance of long-term debt	0	50,000,000
Repayment of long-term debt	0	(50,000,000)
Excess tax benefits from share-based payment arrangements	164,000	414,000
Net proceeds from issuance of common stock	3,054,000	4,703,000
Common stock dividends	(31,435,000)	(24,394,000)
Preferred stock dividends of subsidiaries	(473,000)	(473,000)
Other	(3,953,000)	(3,240,000)
Net cash provided by financing activities	103,895,000	107,278,000
Net increase in cash and cash equivalents	49,084,000	43,046,000
Cash and cash equivalents, beginning of period	220,036,000	219,662,000
Cash and cash equivalents, end of period	$ 269,120,000	$ 262,708,000