Earnings per Share and Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes									$ 28,343	$ 27,432	$ 47,321
Document Fiscal Year Focus									2018
Numerator [Abstract]
Net income (loss) attributable to common stockholders	$ 78,904	$ 69,722	$ 47,841	$ 52,660	$ 85,138	$ 59,666	$ 48,368	$ (33,223)
Income per common share - basic (note 13):
Continuing operations (in dollars per share)	$ 0.47	$ 0.41	$ 0.28	$ 0.31	$ 0.50	$ 0.35	$ 0.28	$ (0.26)
Income per common share - diluted (note 13):
Continuing operations (in dollars per share)					$ 0.50	$ 0.35	$ 0.28	$ (0.26)
Earnings Per Common Unit - Diluted [Abstract]
Weighted Average Limited Partnership Units Outstanding, Basic									349,902	295,054	154,170
Parent Company [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes									$ 28,343	$ 27,432	$ 47,321
Numerator [Abstract]
Net income (loss) attributable to common stockholders									$ 249,127	$ 159,949	$ 143,860
Denominator [Abstract]
Weighted average common shares/units outstanding for basic EPS/EPU									169,724,000	159,536,000	100,863,000
Income per common share - basic (note 13):
Continuing operations (in dollars per share)									$ 1.47	$ 1.00	$ 1.43
Income per common share - diluted (note 13):
Continuing operations (in dollars per share)									$ 1.46	$ 1.00	$ 1.42
Earnings Per Common Unit - Diluted [Abstract]
Weighted average common shares outstanding for diluted EPS (1)									170,100,000	159,960,000	101,285,000
Partnership Interest [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes									$ 28,343	$ 27,432	$ 47,321
Denominator [Abstract]
Weighted average common shares/units outstanding for basic EPS/EPU									170,074,000	159,831,000	101,017,000
Income per common share - basic (note 13):
Continuing operations (in dollars per share)									$ 1.47	$ 1.00	$ 1.43
Income per common share - diluted (note 13):
Continuing operations (in dollars per share)									1.46	1.00	1.42
Earnings Per Common Unit, Basic [Abstract]
Continuing operations (in dollars per share)									1.47	1.00	1.43
Earnings Per Common Unit - Diluted [Abstract]
Continuing operations (in dollars per share)									$ 1.46	$ 1.00	$ 1.42
Weighted average common shares outstanding for diluted EPS (1)									170,450,000	160,255,000	101,439,000
Continuing operations | Parent Company [Member]
Numerator [Abstract]
Net income (loss) attributable to common stockholders									$ 249,127	$ 159,949	$ 143,860
Earnings Per Common Unit - Diluted [Abstract]
Net Income (Loss) Available to Common Stockholders, Diluted									249,127	159,949	143,860
Continuing operations | Partnership Interest [Member]
Numerator [Abstract]
Net income (loss) attributable to common stockholders									249,652	160,337	144,117
Earnings Per Common Unit - Diluted [Abstract]
Net Income (Loss) Available to Common Stockholders, Diluted									$ 249,652	$ 160,337	$ 144,117