CONSOLIDATED STATEMENT OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash flows provided by (used in) operating activities:
Net earnings	$ 255,424	$ 224,548	$ 179,580
Adjustments to reconcile net earnings to net cash flows provided by (used in) operating activities:
Depreciation and amortization	237,690	228,637	213,827
Deferred income taxes	103,538	107,418	121,210
Provision for bad debts	8,089	8,681	8,601
Unrealized loss on commodity derivatives	50	18,514	44,778
Loss from discontinued operations	0	18,100	0
Loss on asset sales or dispositions	1,578	1,867	5,563
Stock-based compensation expense	10,149	9,331	7,510
Earnings from unconsolidated investments, adjusted for cash distributions	(95,605)	(101,915)	(80,790)
Changes in operating assets and liabilities:
Accounts receivable, billed and unbilled	31,456	(41,386)	45,452
Accounts payable and accrued liabilities	(10,390)	(8,508)	12,838
Deferred natural gas purchase costs	37,095	(2,883)	(73,174)
Inventories	(5,848)	(2,964)	76,098
Prepaids and other assets	(1,938)	(1,534)	60,748
Taxes and other liabilities	(38,809)	17,831	(57,962)
Deferred charges	19,022	6,891	(266)
Deferred credits	(20,460)	(57,957)	15,200
Net cash flows provided by operating activities	531,041	424,671	579,213
Cash flows provided by (used in) investing activities:
Additions to property, plant and equipment	(290,290)	(293,022)	(405,381)
Contributions to unconsolidated investments	0	(100,000)	(3,250)
Loan to unconsolidated investments	(72,000)	0
Loan repayment from unconsolidated investments	35,000	0	0
Plant retirements and other	(743)	531	(10,793)
Net cash flows used in investing activities	(328,033)	(392,491)	(419,424)
Cash flows provided by (used in) financing activities:
Increase (decrease) in book overdraft	8,975	(14,154)	8,583
Issuance of long-term debt	0	101,019	303,905
Renewal cost for credit facilities and issuance costs of debt	(2,162)	(7,066)	(4,011)
Issuance of common stock	0	0
Dividends paid on common stock	(74,811)	(74,668)	(74,424)
Dividends paid on preferred stock	0	(7,211)	(8,683)
Extinguishment of preferred stock	0	(115,000)
Repayment of long-term debt obligation	(18,556)	(140,947)	(60,623)
Net change in revolving credit facilities and short-term debt	(97,051)	217,051	(321,459)
Other	938	1,550	3,150
Net cash flows provided by (used in) financing activities	(182,667)	(39,426)	(153,562)
Change in cash and cash equivalents	20,341	(7,246)	6,227
Cash and cash equivalents at beginning of period	3,299	10,545	4,318
Cash and cash equivalents at end of period	23,640	3,299	10,545
Cash paid for interest (net of amounts capitalized)	213,625	212,442	217,437
Cash (received) paid during the period for income taxes	$ (10,918)	$ (20,088)	$ 486

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Includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the Entity may deposit additional funds at any time and also effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Compensating balance arrangements that do not legally restrict the withdrawal or usage of cash amounts may be reported as Cash and Cash Equivalents, while legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or company statements of intention with regard to particular deposits are not generally reported as cash and cash equivalents. Includes cash and cash equivalents associated with the entity's continuing operations. Excludes cash and cash equivalents associated with the disposal group (and discontinued operation).