Partners' Capital, Equity and Incentive Compensation Plans (Summary of Assumptions and Fair Values for Restricted Stock and Options to Purchase Shares of Class A Common Stock Granted) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of restricted stock granted			$ 21.00
Expected volatility	33.00%	33.00%
Expected dividend yield		4.55%	5.50%
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of restricted stock granted	$ 35.81	$ 25.51
Fair value of options granted	$ 8.00	$ 4.94	$ 3.45
Expected term (years)	5 years 6 months	5 years 6 months	5 years 6 months
Expected volatility			32.00%
Expected dividend yield	3.40%	4.02%
Expected risk-free interest rates	1.67%	1.70%	1.40%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of restricted stock granted	$ 37.69	$ 35.51
Fair value of options granted	$ 8.77	$ 5.98	$ 3.52
Expected term (years)	6 years 1 month 6 days	6 years 1 month 6 days	7 years
Expected volatility		4.55%	40.00%
Expected dividend yield	3.57%
Expected risk-free interest rates	1.94%	1.90%	1.80%
Class O Units [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of restricted stock granted			$ 10.26
Class O Units [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of restricted stock granted			$ 10.92