Consolidated Statement of Changes in Equity - USD ($) $ in Thousands	Total	Parent Company [Member]	Partnership Interest [Member]	Preferred Stock Parent Company [Member]	Common Stock Parent Company [Member]	Treasury Stock Parent Company [Member]	Partners Capital Total [Member]	Distributions in Excess of Net Income Parent Company [Member]	Total Stockholders' Equity [Member] Parent Company [Member]	Noncontrolling Interest Exchangeable Operating Partnership Units [Member] Parent Company [Member]	Noncontrolling Interests in Limited Partners Interest in Consolidated Partnerships [Member] Parent Company [Member]	Noncontrolling Interest [Member] Parent Company [Member]	Additional Paid-in Capital [Member] Parent Company [Member]	AOCI Attributable to Parent [Member]	AOCI Attributable to Parent [Member] Parent Company [Member]	Common Stock Parent Company [Member]	Common Stock Preferred Stock Parent Company [Member]	Common Stock Common Stock Parent Company [Member]	Common Stock Treasury Stock Parent Company [Member]	Common Stock Distributions in Excess of Net Income Parent Company [Member]	Common Stock Total Stockholders' Equity [Member] Parent Company [Member]	Common Stock Noncontrolling Interest Exchangeable Operating Partnership Units [Member] Parent Company [Member]	Common Stock Noncontrolling Interests in Limited Partners Interest in Consolidated Partnerships [Member] Parent Company [Member]	Common Stock Noncontrolling Interest [Member] Parent Company [Member]	Common Stock Additional Paid-in Capital [Member] Parent Company [Member]	Common Stock AOCI Attributable to Parent [Member] Parent Company [Member]	Limited Partner [Member]	General Partner Preferred and Common Units	AOCI Attributable to Parent [Member]	Partners Capital Total [Member]	Noncontrolling Interest [Member]
Common stock/unit per share	$ 1.88
Net proceeds from common stock issuance		$ 102,453														$ 102,453
Beginning balance at Dec. 31, 2013	$ (1,861,134)	(1,861,134)		$ (325,000)	$ (923)	$ 16,726		$ 874,916	$ (1,843,354)	$ 1,426	$ (19,206)	$ (17,780)	$ (2,426,477)		$ 17,404												$ 1,426	$ (1,860,758)	$ 17,404	$ (1,841,928)	$ (19,206)
Other comprehensive (loss) income:
Net income	188,847	188,847	$ 188,847	0	0	0			187,390	319	1,138		0		0												319	187,390	0	187,709	1,138
Net Income (Loss) Attributable to Noncontrolling Interest		1,457	1,138
Net Income (Loss) Attributable to Parent		187,390	187,709
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax		(9,353)	(9,353)
Current period other comprehensive income, net	(40,615)	(40,615)	(40,615)	0	0	0		0	(40,344)	(70)	(201)		0	$ (40,344)	(40,344)												(70)	0	(40,344)	(40,414)
Other Comprehensive (Income) Loss, Net of Tax, Portion Attributable to Noncontrolling Interest		(271)	(201)
Adjustments to Additional Paid in Capital, Share-based Compensation, Other Long-term Incentive Plans, Requisite Service Period Recognition		0		0	0	(2,656)		0	0	0	0	0	2,656		0
Restricted stock issued, net of amortization	12,161	12,161		0	0	0	$ 12,161	0	12,161	0	0	0	12,161		0												0	12,161	0		0
Adjustments Related to Tax Withholding for Share-based Compensation				0	0	0				0						3,493				$ 0	$ 3,493		$ 0	$ 0	$ 3,493	$ 0
Stock Issued During Period, Value, Dividend Reinvestment Plan		1,184	1,184	0	0	0				0						1,184				0	1,184		0	0	1,184	0
Common stock issued for stock offerings, net of issuance costs				0	(18)	0				0										0	(102,453)		0	0	(102,435)	0
Common stock issued for partnership units exchanged		(137)	(137)													0	$ 0	$ 0	$ 0	0	(137)	$ (137)	0	(137)	(137)	0
Partners' Capital Account, Redemptions	(300)	(300)		0	0	0		0	0	(300)	0	(300)	0		0												(300)	0	0	(300)	0
Contributions from partners	16,204	16,204		0	0	0		0	0	0	16,204	16,204	0		0												0	0	0	0	16,204
Partners' Capital Account, Distributions		5,947		0	0	0		0	1,404	0	4,543	4,543	1,404		0
Distributions To Partners	(180,031)																										(300)	(175,188)	0	(175,488)	(4,543)
Cash dividends declared:
Preferred stock/unit	(21,062)	(21,062)		0	0	0	21,062	21,062	(21,062)	0	0	0	0		0												0	21,062	0		0
Preferred stock dividends		(21,062)
Common stock/unit		(174,084)		0	0	0		(173,784)	(173,784)	(300)	0	(300)	0		0
Ending Balance at Dec. 31, 2014	(1,936,482)	(1,936,482)		(325,000)	(941)	19,382		882,372	(1,906,592)	1,914	(31,804)	(29,890)	(2,540,153)		57,748												1,914	(1,964,340)	57,748	(1,904,678)	(31,804)
Cash dividends declared:
Common unit issued as a result of common stock issued by Parent Company, net of purchases	100,144						100,144																				0	100,144	0		0
Common units exchanged for common stock of the parent company	$ 0						0																				137	(137)	0		0
Common stock/unit per share	$ 1.94
Net proceeds from common stock issuance		198,494
Net income	$ 152,543	152,543	152,543	0	0	0			150,056	240	2,247		0		0												240	150,056	0	150,296	2,247
Net Income (Loss) Attributable to Noncontrolling Interest		2,487	2,247
Net Income (Loss) Attributable to Parent		150,056	150,296
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax		(9,152)	(9,152)
Current period other comprehensive income, net	(980)	(980)	(980)	0	0	0		0	(945)	(2)	(33)		0	(945)	(945)												(2)	0	(945)	(947)
Other Comprehensive (Income) Loss, Net of Tax, Portion Attributable to Noncontrolling Interest		(35)	(33)
Adjustments to Additional Paid in Capital, Share-based Compensation, Other Long-term Incentive Plans, Requisite Service Period Recognition		0		0	0	(276)		0	0	0	0	0	276		0
Restricted stock issued, net of amortization	13,869	13,869		0	0	0	13,869	0	13,869	0	0	0	13,869		0												0	13,869	0		0
Adjustments Related to Tax Withholding for Share-based Compensation																9,706	0	0	0	0	9,706	0	0	0	9,706	0
Stock Issued During Period, Value, Dividend Reinvestment Plan		1,250	1,250													1,250	0	0	0	0	1,250	0	0	0	1,250	0
Common stock issued for stock offerings, net of issuance costs																(198,494)	0	(31)	0	0	(198,494)	0	0	0	(198,463)	0
Common stock issued for partnership units exchanged		0	0
Contributions from partners	717	717		0	0	0		0	0	0	717	717	0		0												0	0	0	0	717
Partners' Capital Account, Distributions		6,046		0	0	0		0	1,797	0	4,249	4,249	1,797		0
Distributions To Partners	(188,987)																										(299)	(184,439)	0	(184,738)	(4,249)
Preferred stock/unit	(21,062)	(21,062)		0	0	0	21,062	21,062	(21,062)	0	0	0	0		0												0	21,062	0		0
Preferred stock dividends		(21,062)
Common stock/unit		(182,941)		0	0	0		(182,642)	(182,642)	(299)	0	(299)	0		0
Ending Balance at Dec. 31, 2015	(2,082,620)	(2,082,620)	(2,082,620)	(325,000)	(972)	19,658		936,020	(2,054,109)	1,975	(30,486)	(28,511)	(2,742,508)		58,693												1,975	(2,112,802)	58,693	(2,052,134)	(30,486)
Cash dividends declared:
Common unit issued as a result of common stock issued by Parent Company, net of purchases	190,038						190,038																				0	190,038	0		0
Noncontrolling Interest, Decrease from Deconsolidation	$ 0	0		0	0	0		0	(538)	0	538	538	(538)		0												0	(538)	0	(538)	538
Common stock/unit per share	$ 2.00
Net proceeds from common stock issuance		548,920
Net income	$ 166,992	166,992	166,992	0	0	0			164,922	257	1,813		0		0												257	164,922	0	165,179	1,813
Net Income (Loss) Attributable to Noncontrolling Interest		2,070	1,813
Net Income (Loss) Attributable to Parent		164,922	165,179
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax		(51,139)	(51,139)
Current period other comprehensive income, net	40,831	40,831	40,831	0	0	0		0	40,347	58	426		0	$ 40,347	40,347												58	0	40,347	40,405
Other Comprehensive (Income) Loss, Net of Tax, Portion Attributable to Noncontrolling Interest		484	426
Adjustments to Additional Paid in Capital, Share-based Compensation, Other Long-term Incentive Plans, Requisite Service Period Recognition		0		0	0	(2,596)		0	0	0	0	0	(2,596)		0
Restricted stock issued, net of amortization	13,421	13,421		0	2	0	13,421	0	13,421	0	0	0	13,419		0												0	13,421	0		0
Adjustments Related to Tax Withholding for Share-based Compensation																7,789	0	0	0	0	7,789	0	0	0	7,789	0
Stock Issued During Period, Value, Dividend Reinvestment Plan		1,070	1,070													1,070	0	0	0	0	1,070	0	0	0	1,070	0
Common stock issued for stock offerings, net of issuance costs																$ (548,920)	$ 0	$ (71)	$ 0	$ 0	$ (548,920)	$ 0	$ 0	$ 0	$ (548,849)	$ 0
Common stock issued for partnership units exchanged		0	0
Partners' Capital Account, Redemptions	0																										0	0	0	0	0
Contributions from partners	8,760	8,760		0	0	0		0	0	0	8,760	8,760	0		0												0	0	0	0	8,760
Partners' Capital Account, Distributions		6,855		0	0	0		0	0	0	6,855	6,855	0		0
Distributions To Partners	(209,261)																										(307)	(202,099)	0	(202,406)	(6,855)
Preferred stock/unit	(21,062)	(21,062)		0	0	0	21,062		(21,062)	0	0	0	0		0												0	21,062	0		0
Preferred stock dividends		(21,062)
Common stock/unit		(202,406)		0	0	0		(202,099)	(202,099)	(307)	0	(307)	0		0
Ending Balance at Dec. 31, 2016	(2,624,502)	$ (2,624,502)	$ (2,624,502)	$ (325,000)	$ (1,045)	$ 17,062		$ 994,259	$ (2,591,301)	$ 1,967	$ (35,168)	$ (33,201)	$ (3,294,923)		$ 18,346												1,967	(2,609,647)	18,346	$ (2,589,334)	(35,168)
Cash dividends declared:
Common unit issued as a result of common stock issued by Parent Company, net of purchases	$ 542,201						$ 542,201																				$ 0	$ 542,201	$ 0		$ 0