Incentive Plan (Class C Profits Interest Units) (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified			9 Months Ended		9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Class C Profit Units [Member] item	May 01, 2010 Class C Profit Units [Member]	Sep. 30, 2013 Restricted Stock [Member]	May 01, 2010 Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards satisfying market conditions on measurement date				593,316		20,169
Vesting based on market conditions with respect to the first measurement date not achieved			Of the Class C Units that satisfied the market condition on May 1, 2010, 60% vested on May 1, 2010 and the remaining 40% vested ratably each month through June 30, 2012.		The service conditions of the awards provide for 20% vesting on each of the first and second anniversaries of the grant date and 30% vesting on each of the third and fourth anniversaries of the grant date provided the grantee continues employment on each anniversary date.
Award vesting percentage, vested				60.00%
Award vesting percentage, unvested				40.00%
Approximate number of times simulation was run			100,000
Expected term			36 months
Expected volatility rate			23.00%
Risk-free interest rate			4.60%
Expected dividend rate			5.00%
Award limit, first market condition			$ 17
Award limit, second market condition			40
Common Stock, shares outstanding	128,438,970	125,140,783	69,200,000
Grant date fair value of awards			$ 11.8
Requisite service period of share-based award			5 years