Common Shares (Tables)

12 Months Ended

Dec. 31, 2012

2010 and 2011 ATM Programs [Member]

Activity Under At-The-Market Share Offering Program

The following table presents activity under our 2010 and 2011 ATM programs for the periods presented (in thousands, except per share amounts):

	Year Ended December 31,
	2012		2011		2010
Total net consideration	$	128,128.0	$	106,570.6	$	231,650.5
Common shares sold	1,971.4		1,751.0		4,867.7
Average price per share	$	66.01	$	61.95	$	48.37

2012 ATM Program [Member]

Activity Under At-The-Market Share Offering Program

The following table presents activity under our 2012 ATM program for the period presented (in thousands, except per share amounts):

	Year Ended December 31, 2012
Total net consideration	$	173,607.5
Common shares sold	2,607.9
Average price per share	$	67.63