Stock-Based Compensation (tables)

12 Months Ended

Dec. 31, 2012

Share-based Compensation [Abstract]

Schedule Of Performance Based Award [Table Text Block]

	Performance Shares Awards Outstanding				2012		Cumulative Expense
Performance Period	Target		Maximum		Expense		At Dec. 31, 2012
2010-12	$	41,500	$	83,000	$	452	$	1,170
2011-13	37,950		75,900		294		570
2012-14	35,340		70,680		635		635
Total	$	114,790	$	229,580	$	1,381

SOP Assumptions [Table Text Block]

	2011			2010
Risk-free interest rate	2.0		%	2.3		%
Expected life (in years)	4.5			4.7
Expected market price volatility factor	24.5		%	23.2		%
Expected dividend yield	3.8		%	3.8		%
Forfeiture rate	3.1		%	3.2		%
Weighted average grant date fair value	$	6.73		$	6.36

Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]

	Option Shares		Weighted - Average Price Per Share		Intrinsic Value (In millions)
Balance outstanding, Dec. 31, 2009	484,935		$	39.57	$	2.7
Granted	119,750		44.25		n/a
Exercised	(111,525	)	39.01		0.9
Forfeited	(2,700	)	43.00		n/a
Balance outstanding, Dec. 31, 2010	490,460		40.82		2.8
Granted	122,700		45.74		n/a
Exercised	(24,185	)	33.88		0.3
Forfeited	(9,750	)	44.38		n/a
Balance outstanding, Dec. 31, 2011	579,225		42.09		3.4
Exercised	(46,825	)	40.62		0.4
Forfeited	(2,475	)	43.78		n/a
Balance outstanding, Dec. 31, 2012	529,925		42.22		1.3
Exercisable, Dec. 31, 2012	366,887		41.16		1.2

Schedule Of Stock Based Compensation Capitalized Under LTIP SOP and ESPP [Table Text Block]

In thousands	2012			2011			2010
Operations and maintenance expense, for stock-based compensation	$	1,668		$	1,477		$	1,032
Income tax benefit	(707		)	(597		)	(418		)
Net stock-based compensation effect on net income	$	961		$	880		$	614
Amounts capitalized for stock-based compensation	$	294		$	261		$	182