Consolidated Statements Of Cash Flow (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Cash flows from operating activities:
Net income	$ 79,349	$ 67,941
Income from discontinued operations	9,064	700
Income from continuing operations	70,285	67,241
Adjustments to reconcile income from continuing operations to net cash flows from operating activities:
Depreciation and amortization	59,046	56,087
Deferred income taxes	39,168	32,335
Provision for doubtful accounts	2,014	2,142
Stock-based compensation	2,867	1,671
Gain on sale of utility system	(328)	(4,317)
Gain on sale of other assets	(506)	(259)
Net increase in receivables, inventory and prepayments	(12,155)	(16,961)
Net increase in payables, accrued interest, accrued taxes and other accrued liabilities	5,235	1,282
Other	(6,471)	(6,902)
Operating cash flows from continuing operations	159,155	132,319
Operating cash flows (used in) from discontinued operations, net	(13,813)	3,625
Net cash flows from operating activities	145,342	135,944
Cash flows from investing activities:
Property, plant and equipment additions, including allowance for funds used during construction of $2,588 and $3,906	(171,424)	(141,276)
Acquisitions of utility systems and other, net	(103,998)	(6,533)
Additions to funds restricted for construction activity	(2,080)	(119)
Release of funds previously restricted for construction activity	35,896	794
Net proceeds from the sale of utility system and other assets	4,727	11,498
Proceeds from note receivable		5,289
Other	(10,700)	(383)
Investing cash flows used in continuing operations	(247,579)	(130,730)
Investing cash flows (used in) discontinued operations, net	74,500	(1,568)
Net cash flows used in investing activities	(173,079)	(132,298)
Cash flows from financing activities:
Customers' advances and contributions in aid of construction	3,785	2,292
Repayments of customers' advances	(1,428)	(1,271)
Net (repayments) proceeds of short-term debt	(48,079)	29,216
Proceeds from long-term debt	168,076	22,293
Repayments of long-term debt	(45,106)	(23,322)
Change in cash overdraft position	(20,375)	214
Proceeds from issuing common stock	6,429	6,388
Proceeds from exercised stock options	7,873	5,567
Stock-based compensation windfall tax benefits	409
Repurchase of common stock	(1,132)	(998)
Dividends paid on common stock	(45,872)	(42,813)
Financing cash flows from (used in) continuing operations	24,580	(2,434)
Financing cash flows used in discontinued operations, net		(229)
Net cash flows from (used in) financing activities	24,580	(2,663)
Net (decrease) increase in cash and cash equivalents	(3,157)	983
Cash and cash equivalents at beginning of period	8,204	5,934
Cash and cash equivalents at end of period	$ 5,047	$ 6,917