Earnings per Share Impact on Diluted Shares of Conversion of TEUs (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Weighted Average Number of Shares Outstanding, Diluted	56,676	43,153	56,633	43,116
Minimum [Member] | Tangible Equity Units [Member]
Share Price	$ 80.94		$ 80.94
Tangible Equity Units Number Of Shares Upon Conversion Total	2,842		2,842
Weighted Average Number of Shares Outstanding, Diluted	56,676
Middle [Member] | Tangible Equity Units [Member]
Share Price	$ 73.00		$ 73.00
Tangible Equity Units Number Of Shares Upon Conversion Total	3,151		3,151
Weighted Average Number of Shares Outstanding, Diluted	56,985
Maximum [Member] | Tangible Equity Units [Member]
Share Price	$ 64.75		$ 64.75
Tangible Equity Units Number Of Shares Upon Conversion Total	3,552		3,552
Weighted Average Number of Shares Outstanding, Diluted	57,386