Net Income Per Common Unit (Details) (USD $)
In Thousands, except Share data, unless otherwise specified
 3 Months Ended 12 Months Ended
Dec. 31, 2012
Sep. 30, 2012
Jun. 30, 2012
Mar. 31, 2012
Dec. 31, 2011
Sep. 30, 2011
Jun. 30, 2011
Mar. 31, 2011
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Net Income (Loss) Available to Common Stockholders, Basic [Abstract]                      
Net income from continuing operations $ 6,568 $ 7,953 $ (7,140) $ 45,949 $ 53,004 $ (8,549) $ 21,146 $ 12,788 $ 53,330 $ 78,389 $ 16,802
Decrease in deferred fee liability                 0 [1] (6,107) [1] 0 [1]
Restricted stock expense                 121 0 0
Net income attributable to noncontrolling interests in consolidated entities                 (17,977) (44,521) (248)
Net income from continuing operations                 35,474 27,761 16,554
Income from discontinued operations                 10,435 2,888 29,644
Net (income) attributable to noncontrolling interests                 (4,770) (1,287) (14,451)
Income from discontinued operations, net of tax, attributable to parent                 5,665 1,601 15,193
Net income attributable to common unitholders                 $ 41,139 $ 29,362 $ 31,747
Earnings Per Share, Basic, Two Class Method [Abstract]                      
Net income from continuing operations (in dollars per unit) (0.03) 0.09 (0.33) 1.74 0.90 (0.50) 0.50 0.44 1.19 1.34 0.66
Net income from discontinued operations (in dollars per unit)                 0.19 0.07 0.60
Net income attributable to common unitholders (in dollars per unit) 0.06 0.11 (0.33) 1.83 0.92 (0.50) 0.50 0.49 1.38 1.41 1.26
Earnings Per Share, Diluted, Two Class Method [Abstract]                      
Net income from continuing operations (in dollars per unit) (0.03) 0.09 (0.33) 1.74 0.81 0.76 0.50 0.39 1.19 0.94 0.60
Net income from discontinued operations (in dollars per unit)                 0.19 0.05 0.56
Net income attributable to common unitholders (in dollars per unit) 0.06 0.11 (0.33) 1.83 0.81 (0.75) 0.50 0.43 1.38 0.99 1.16
Weighted Average Number of Shares Outstanding, Basic [Abstract]                      
Weighted average common units outstanding - basic (in shares)                 29,748,746 25,232,985 25,234,827
Weighted Average Number Diluted Shares Outstanding Adjustment [Abstract]                      
Adjustment for deferred fee liabilities (in shares)                 0 [1] 4,021,933 [1] 0 [1]
Adjustment for distribution payable (in shares)                 0 [2] 414,110 [2] 2,247,977 [2]
Unvested restricted stock (in shares)                 25,781 554 0
Denominator for net income per common unit - diluted (in shares)                 29,774,527 29,669,582 27,482,804
[1] Includes common units assuming a common unit settlement of the deferred fee liability as described in Note 13 - “Related Party Transactions.”
[2] Includes common units assuming a common unit settlement of the distribution payable. The Target Distribution liability described in Note 16 - "Capital and Accumulated Other Comprehensive Loss" may be settled in common units.