Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash flows from operating activities
Net income	$ 75,213	$ 78,062
Adjustments to reconcile net income to net cash provided by (used in) operating activities
Depreciation of property, plant and equipment	79,843	75,517
Other amortization	2,868	2,999
Provision for loan losses	899	5,924
Loans receivable originated and purchased, held for sale	(128,276)	(161,344)
Proceeds from sale of loans receivable, held for sale	148,243	161,713
Change in deferred income taxes	40,403	41,541
Change in excess tax benefits from share-based payment arrangements	(445)	(40)
Allowance for equity funds used during construction	(2,775)	(3,937)
Changes in assets and liabilities
Decrease (increase) in accounts receivable and unbilled revenues, net	3,564	(42,428)
Decrease (increase) in fuel oil stock	43,974	(35,893)
Increase in regulatory assets	(37,586)	(35,476)
Increase (decrease) in accounts, interest and dividends payable	(43,384)	3,578
Change in prepaid and accrued income taxes and utility revenue taxes	(33,822)	(12,998)
Contributions to defined benefit pension and other postretirement benefit plans	(41,521)	(53,356)
Other increase in defined benefit pension and other postretirement benefit plans liability	41,191	31,204
Change in other assets and liabilities	(17,597)	(58,638)
Net cash provided by (used in) operating activities	130,792	(3,572)
Cash flows from investing activities
Available-for-sale investment and mortgage-related securities purchased	(39,721)	(93,808)
Principal repayments on available-for-sale investment and mortgage-related securities	62,819	75,407
Proceeds from sale of available-for-sale investment and mortgage-related securities	71,367	3,548
Net increase in loans held for investment	(201,184)	(61,214)
Proceeds from sale of real estate acquired in settlement of loans	5,712	6,036
Capital expenditures	(158,830)	(145,263)
Contributions in aid of construction	17,188	26,981
Other	2,364
Net cash used in investing activities	(240,285)	(188,313)
Cash flows from financing activities
Net increase in deposit liabilities	46,326	66,709
Net increase in short-term borrowings with original maturities of three months or less	42,093	27,419
Net decrease in retail repurchase agreements	(8,054)	(14,556)
Proceeds from other bank borrowings	25,000
Repayments of other bank borrowings	(25,000)
Proceeds from issuance of long-term debt	50,000	417,000
Repayment of long-term debt	(50,000)	(328,500)
Change in excess tax benefits from share-based payment arrangements	445	40
Net proceeds from issuance of common stock	11,994	11,909
Common stock dividends	(48,921)	(47,851)
Preferred stock dividends of subsidiaries	(946)	(946)
Other	606	(2,055)
Net cash provided by financing activities	43,543	129,169
Net decrease in cash and cash equivalents	(65,950)	(62,716)
Cash and cash equivalents, beginning of period	219,662	270,265
Cash and cash equivalents, end of period	$ 153,712	$ 207,549