Share-Based Compensation (Schedule Of Performance Vesting Restricted Stock Units Granted) (Details)	6 Months Ended		12 Months Ended
	Jun. 30, 2013		Dec. 31, 2012		Dec. 31, 2011
Share-based Compensation, Allocation and Classification in Financial Statements [Abstract]
Three-year performance period ending December 31,	2015		2014		2013
Vesting shares, target	84,500	[1]	89,000	[1]	80,000	[1]
Vesting shares, maximum	190,125	[1]	200,250	[1]	120,000	[1]

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