Partners' Capital, Equity and Incentive Compensation Plans (Summary of Award Activity Under 2010 Equity Incentive Plan and 2013 Equity Incentive Plan and Related Information) (Details)	3 Months Ended
	Mar. 31, 2016 $ / shares shares
2013 Equity Incentive Plan [Member] | Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning balance, Options Outstanding | shares	867,882
Options, Granted | shares	229,693
Options, Exercised | shares	(5,063)
Options, Released from restriction | shares		[1]
Options, Cancelled/Expired | shares	(1,250)	[2]
Ending balance, Options Outstanding | shares	1,091,262
Beginning balance, Weighted average exercise price options outstanding	$ 27.80
Weighted average exercise price options outstanding, Granted	45.78
Weighted average exercise price options outstanding, Exercised	$ 26.00
Weighted average exercise price options outstanding, Released from restriction		[1]
Weighted average exercise price options outstanding, Cancelled/Expired	$ 28.82	[2]
Ending balance, Weighted average exercise price options outstanding	31.59
Beginning balance, weighted average fair value, options	5.56
Weighted average fair value, granted, options	9.91
Weighted average fair value, vested, options	$ 5.21
Weighted average fair value, released from restriction, options		[1]
Weighted average fair value, cancelled/expired, options	$ 5.98	[2]
Ending balance, weighted average fair value, options	$ 6.47
2013 Equity Incentive Plan [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning balance, Number of units | shares	394,908
Number of units, Granted | shares	205,508
Number of units, Exercised | shares	(45,890)	[3]
Number of units, Released from restriction | shares		[1]
Number of units, Cancelled/Expired | shares	(21,335)	[2]
Ending balance, Number of units | shares	533,191
Beginning balance, Weighted average fair value	$ 33.82
Weighted average fair value, Granted	45.89
Weighted average fair value, Exercised	$ 33.93
Weighted average fair value, Released from restriction		[1]
Weighted average fair value, Cancelled/Expired	$ 35.44	[2]
Ending balance, Weighted average fair value	$ 38.40
Restricted Class A Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units surrendered | shares	21,335
Class O Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Ending balance, Number of units | shares	200,000
Class O Units [Member] | 2010 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning balance, Number of units | shares	1,292,899
Number of units, Granted | shares
Number of units, Exercised | shares	(21,925)
Number of units, Released from restriction | shares		[1]
Number of units, Cancelled/Expired | shares		[2]
Ending balance, Number of units | shares	1,270,974
Beginning balance, Weighted average exercise price units	$ 23.76
Weighted average exercise price units, Granted
Weighted average exercise price units, Exercised	$ 23.15
Weighted average exercise price units, Released from restriction		[1]
Weighted average exercise price units, Cancelled/Expired		[2]
Ending balance, Weighted average exercise price units	$ 23.77
Beginning balance, Weighted average fair value	$ 3.68
Weighted average fair value, Granted
Weighted average fair value, Exercised	$ 3.36
Weighted average fair value, Released from restriction		[1]
Weighted average fair value, Cancelled/Expired		[2]
Ending balance, Weighted average fair value	$ 3.68
Class RS Units [Member] | 2010 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning balance, Number of units | shares	39,875
Number of units, Granted | shares
Number of units, Exercised | shares
Number of units, Released from restriction | shares	(31,187)	[1]
Number of units, Cancelled/Expired | shares		[2]
Ending balance, Number of units | shares	8,688
Beginning balance, Weighted average fair value	$ 22.18
Weighted average fair value, Granted
Weighted average fair value, Exercised
Weighted average fair value, Released from restriction	$ 21.39	[1]
Weighted average fair value, Cancelled/Expired		[2]
Ending balance, Weighted average fair value	$ 25.00

[1] This represents Class RS units that upon vesting have converted to Operating Partnership units

[2] Includes 21,335 restricted Class A common stock surrendered by certain employees to satisfy their statutory minimum federal and state tax obligations associated with the vesting of restricted common stock.

[3] This represents the Class A common stock that has been released from restriction and which was not surrendered by the holder to satisfy their statutory minimum federal and state tax obligations associated with the vesting of restricted common stock