Consolidated Statement of Changes in Partner Capital Statement - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015
Dividends, Preferred Stock, Cash	$ 3,241	$ 5,266
Shareholders' Equity	6,764,503	2,082,373	$ 2,624,502	$ 2,082,620
Net income	(20,715)	53,577
Other comprehensive income (loss)	2,620	(14,368)
Partners' Capital Account, Contributions	153	8,389
Partners' Capital Account, Distributions	54,317	50,616
Common unit issued as a result of common stock issued by Parent Company, net of purchases	4,461,767	4,635
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	3,733	3,402
Stockholders Equity including noncontrolling interest	6,764,502
Noncontrolling Interest [Member]
Dividends, Preferred Stock, Cash	0	0
Shareholders' Equity	35,217	37,691	35,168	30,486
Net income	671	349
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest	63	(146)
Partners' Capital Account, Contributions	153	8,389
Partners' Capital Account, Distributions	838	1,387
Common unit issued as a result of common stock issued by Parent Company, net of purchases	0	0
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	0	0
Partners Capital Total [Member]
Dividends, Preferred Stock, Cash	3,241	5,266
Shareholders' Equity	6,729,285	2,044,682	2,589,334	2,052,134
Net income	(21,386)	53,228
Other comprehensive income (loss)	2,557	(14,222)
Partners' Capital Account, Contributions	0	0
Partners' Capital Account, Distributions	53,479	49,229
Common unit issued as a result of common stock issued by Parent Company, net of purchases	4,461,767	4,635
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	3,733	3,402
AOCI Attributable to Parent [Member]
Dividends, Preferred Stock, Cash	0	0
Shareholders' Equity	(15,791)	(72,893)	(18,346)	(58,693)
Net income	0	0
Other comprehensive income (loss)	2,555	(14,200)
Partners' Capital Account, Contributions	0	0
Partners' Capital Account, Distributions	0	0
Common unit issued as a result of common stock issued by Parent Company, net of purchases	0	0
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	0	0
Limited Partner [Member]
Dividends, Preferred Stock, Cash	0	0
Shareholders' Equity	(2,063)	(1,989)	(1,967)	(1,975)
Net income	(19)	85
Other comprehensive income (loss)	2	(22)
Partners' Capital Account, Contributions	0	0
Partners' Capital Account, Distributions	79	77
Common unit issued as a result of common stock issued by Parent Company, net of purchases	0	0
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	0	0
General Partner [Member]
Dividends, Preferred Stock, Cash	3,241	5,266
Shareholders' Equity	6,747,139	2,119,564	$ 2,609,647	$ 2,112,802
Net income	(21,367)	53,143
Other comprehensive income (loss)	0	0
Partners' Capital Account, Contributions	0	0
Partners' Capital Account, Distributions	53,400	(49,152)
Common unit issued as a result of common stock issued by Parent Company, net of purchases	4,461,767	4,635
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	3,733	3,402
Partnership Interest [Member]
Net income	(20,715)	53,577
Other comprehensive income (loss)	2,618	(14,368)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest	63	(146)
Deferred Compensation Plan	0
Partnership Interest [Member] | General Partner [Member]
Deferred Compensation Plan	0
Partnership Interest [Member] | Preferred Stock [Member]
Preferred Stock Redemption Premium		(250,000)
Partnership Interest [Member] | Preferred Stock [Member] | General Partner [Member]
Preferred Stock Redemption Premium	(250,000)
Noncontrolling Interests in Limited Partners Interest in Consolidated Partnerships [Member] | Partnership Interest [Member]
Deferred Compensation Plan	0
Noncontrolling Interests in Limited Partners Interest in Consolidated Partnerships [Member] | Partnership Interest [Member] | Preferred Stock [Member]
Preferred Stock Redemption Premium	0
Partners Capital Total [Member] | Partnership Interest [Member]
Deferred Compensation Plan	0
Partners Capital Total [Member] | Partnership Interest [Member] | Preferred Stock [Member]
Preferred Stock Redemption Premium		(250,000)
Limited Partners [Member] | Partnership Interest [Member]
Deferred Compensation Plan	0
Limited Partners [Member] | Partnership Interest [Member] | Preferred Stock [Member]
Preferred Stock Redemption Premium	0
AOCI Attributable to Parent [Member]
Other comprehensive income (loss)	2,554	$ (14,200)
AOCI Attributable to Parent [Member] | Partnership Interest [Member]
Deferred Compensation Plan	0
AOCI Attributable to Parent [Member] | Partnership Interest [Member] | Preferred Stock [Member]
Preferred Stock Redemption Premium	$ 0