MAALP Capital (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Limited Partners' Capital Account [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning Balance	$ 165,726	$ 161,310
Net Income Allocated to Limited Partners	9,508	16,078
General partner units issued in exchange for limited partner units	(780)	(236)
Adjustment for noncontrolling interest ownership in operating partnership	13	58
Distributions	(10,217)	(9,671)
Ending Balance	164,250	167,539
General Partners' Capital Account [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning Balance	2,993,696	2,890,858
Net Income Allocated to General Partners	172,836	289,300
Issuance of units	(738)	326
Units repurchased and retired	(1,811)	(957)
Units Issued During Period, Value, Unit Options Exercised		420
General partner units issued in exchange for limited partner units	780	236
Units issued in exchange for redeemable units	122
Redeemable stock fair market value	(296)	(614)
Adjustment for noncontrolling interest ownership in operating partnership	(13)	(58)
Amortization of unearned compensation	6,625	4,950
Distributions	(185,789)	(174,100)
Ending Balance	2,985,412	3,010,361
Accumulated Other Comprehensive Income (Loss) [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning Balance	(1,618)	(376)
Other comprehensive (loss) income - derivatives insturments (cash flow hedges)	(481)	(6,222)
Ending Balance	(2,099)	(6,598)
Total Partnership Capital [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning Balance	3,157,804	3,051,792
Net Income Available for Common Unitholders	182,344	305,378
Other comprehensive (loss) income - derivatives insturments (cash flow hedges)	(481)	(6,222)
Issuance of units	(738)	326
Units repurchased and retired	(1,811)	(957)
Units Issued During Period, Value, Unit Options Exercised		420
General partner units issued in exchange for limited partner units	0	0
Units issued in exchange for redeemable units	122
Redeemable stock fair market value	(296)	(614)
Adjustment for noncontrolling interest ownership in operating partnership	0	0
Amortization of unearned compensation	6,625	4,950
Distributions	(196,006)	(183,771)
Ending Balance	$ 3,147,563	$ 3,171,302