MAALP Capital (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014 Limited Partners' Capital Account [Member]	Jun. 30, 2014 General Partners' Capital Account [Member]	Jun. 30, 2014 Accumulated Other Comprehensive Income (Loss) [Member]	Jun. 30, 2014 Total Partnership Capital [Member]	Jun. 30, 2013 Prior Period Rollforward [Member] Limited Partners' Capital Account [Member]	Jun. 30, 2013 Prior Period Rollforward [Member] General Partners' Capital Account [Member]	Jun. 30, 2013 Prior Period Rollforward [Member] Accumulated Other Comprehensive Income (Loss) [Member]	Jun. 30, 2013 Prior Period Rollforward [Member] Total Partnership Capital [Member]
Capital Disclosure [Line Items]
Beginning Balance	$ 166,746	$ 2,946,598	$ 174	$ 3,113,518	$ 38,154	$ 927,734	$ (26,881)	$ 939,007
Net Income Allocated to Limited Partners	2,621				2,758
Net Income Allocated to General Partners		46,479				68,535
Net Income Available for Common Unitholders				49,100				71,293
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax			(1,590)	(1,590)			20,381	20,381
Units Issued During Period, Value, New Issues	0	575		575		24,969		24,969
Units Repurchased and Retired During Period, Value		(336)		(336)		(673)		(673)
Units Issued During Period, Value, Unit Options Exercised		9,544		9,544
General Partnership Units Issued in Exchange for Limited Partnership Units	(799)	799		0	(443)	443		0
Partnership units issued in exchange for redeemable units		998		998
Effect On Retained Earnings Accumulated Deficit Due To Fair Value Option And Measurement		(848)		(848)		(431)		(431)
Noncontrolling Interest, Period Increase (Decrease)	(79)	79		0	557	17,259		17,816
Amortization Unearned Compensation		2,045		2,045		1,171		1,171
Distributions	(6,143)	(109,680)		(115,823)	(2,374)	(59,407)		(61,781)
Ending Balance	$ 162,346	$ 2,896,253	$ (1,416)	$ 3,057,183	$ 38,652	$ 979,600	$ (6,500)	$ 1,011,752