Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2012

Stock Based Compensation Tables [Abstract]

Schedule Of Share Based Compensation Stock Options Activity Table Text Block

					Weighted-
			Weighted-		Average
			Average		Remaining	Aggregate
			Exercise		Contractual	Intrinsic
		Shares	Price		Term	Value
Outstanding at January 1, 2012		4,514,341	$	60.96
Granted		47,720		82.86
Exercised		(1,120,193)		42.34
Cancelled or expired		(81,796)		74.39
Outstanding at December 31, 2012		3,360,072	$	67.16	6.1	$	56,414,000
Options vested and expected to vest at
	December 31, 2012	3,353,953	$	67.16	6.1	$	56,313,000
Options exercisable at December 31, 2012		1,970,247	$	68.02	5.4	$	32,914,000

Schedule Of Share Based Payment Award Stock Options Valuation Assumptions Table Text Block

	December 31,
	2012	2011	2010
Expected volatility	36.00%	35.00%	35.00%
Expected life	5.0years	7.1years	7.9years
Risk free interest rate	1.05%	2.90%	3.60%
Expected dividend yield	4.30%	4.40%	4.90%

Schedule Of Sharebased Compensation Restricted Stock And Restricted Stock Units Activity Table Text Block

			Weighted-Average
			Grant-Date
Unvested Shares		Shares	Fair Value
	Unvested at January 1, 2012	61,228	$	79.28
	Granted	11,060		83.96
	Vested	(22,297)		83.61
	Cancelled or expired	(1,971)		72.97
	Unvested at December 31, 2012	48,020		78.61

Schedule Of Sharebased Compensation Restricted Operating Partnership Units Activity Table [Text Block]

			Weighted-Average
			Grant-Date
Unvested Units		Units	Fair Value
	Unvested at January 1, 2012	699,659	$	65.29
	Granted	209,663		78.52
	Vested	(235,245)		63.82
	Cancelled or expired	(33,407)		75.93
	Unvested at December 31, 2012	640,670		69.61