Earnings per Share and Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income per common unit - diluted
Weighted Average Limited Partnership Units Outstanding, Basic			238,987	154,170
Parent Company [Member]
Earnings Per Share [Abstract]
Net income attributable to common stockholders	$ 48,368	$ 34,810	$ 15,144	$ 82,687
Weighted average common units outstanding for basic EPU (in shares)	170,088,000	97,657,000	148,610,000	97,588,000
Weighted average common units outstanding for diluted EPU (in shares)	170,420,000	98,218,000	148,930,000	98,075,000
Income per common share/unit - basic:
Continuing operations (in dollars per share)	$ 0.28	$ 0.36	$ 0.10	$ 0.85
Income per common share/unit - diluted:
Continuing operations (in dollars per share)	$ 0.28	$ 0.35	$ 0.10	$ 0.84
Partnership Interest [Member]
Earnings Per Share [Abstract]
Weighted average common units outstanding for basic EPU (in shares)	170,410,000	97,811,000	148,849,000	97,742,000
Weighted average common units outstanding for diluted EPU (in shares)	170,742,000	98,372,000	149,169,000	98,229,000
Income per common unit - basic
Continuing operations (in dollars per share)	$ 0.28	$ 0.36	$ 0.10	$ 0.85
Income per common unit - diluted
Continuing operations (in dollars per share)	$ 0.28	$ 0.35	$ 0.10	$ 0.84
Continuing Operations [Member] \| Parent Company [Member]
Earnings Per Share [Abstract]
Net income attributable to common stockholders	$ 48,368	$ 34,810	$ 15,144	$ 82,687
Net income for common stock unit/holders - diluted	48,368	34,810	15,144	82,687
Continuing Operations [Member] \| Partnership Interest [Member]
Earnings Per Share [Abstract]
Net income attributable to common stockholders	48,472	34,874	15,229	82,837
Net income for common stock unit/holders - diluted	$ 48,472	$ 34,874	$ 15,229	$ 82,837

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Per unit of ownership amount after tax of income (loss) from continuing operations available to limited partnership (LP) unit-holder and units that would have been outstanding assuming the issuance of limited partner units for dilutive potential units outstanding.

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The amount of net income (loss) from continuing operations per each share of common stock or unit outstanding during the reporting period.

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Per unit of ownership amount after tax of income (loss) from continuing operations available to limited partnership (LP) unit-holder in a publicly trade limited partnership (LP) or master limited partnership (MLP).

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Net income after adjustments for dividends on preferred stock (declared in the period) and/or cumulative preferred stock (accumulated for the period).

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Weighted average number of limited partnership units outstanding determined by relating the portion of time within a reporting period that limited partnership units have been outstanding to the total time in that period.

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