Condensed Consolidated Statements of Changes in Equity - USD ($) shares in Thousands, $ in Thousands	Common Units	Class B Units	Non-controlling Interest	Total
Balance, Equity at Dec. 31, 2013	$ 3,476,295	$ 602,025	$ 719,813	$ 4,798,133
Balance, Equity (in units) at Dec. 31, 2013	157,766	15,964
Increase (Decrease) in Equity
Issuance of units in public offering, net of offering costs	$ 711,837			711,837
Issuance of units in public offering, net of offering costs (in units)	11,284
Distributions paid	$ (278,316)		(90)	(278,406)
Redeemable non-controlling interest classified as temporary equity			164,906	164,906
Elimination of non-controlling interest from deconsolidation of a subsidiary			(6,592)	(6,592)
Share-based compensation activity	$ 1,012			1,012
Share-based compensation activity (in units)	211
Deferred income tax impact from changes in equity	$ (18,304)			(18,304)
Net (loss) income	21,469		7,495	28,964
Balance, Equity at Jun. 30, 2014	$ 3,913,993	$ 602,025	885,532	5,401,550
Balance, Equity (in units) at Jun. 30, 2014	169,261	15,964
Balance, Temporary Equity at Dec. 31, 2013				235,617
Redeemable Non-controlling Interest (Temporary Equity)
Redeemable non-controlling interest classified as temporary equity				(164,906)
Balance, Temporary Equity at Jun. 30, 2014				70,711
Balance, Equity at Dec. 31, 2014	$ 4,758,243	$ 451,519	983,477	6,193,239
Balance, Equity (in units) at Dec. 31, 2014	186,553	11,973
Increase (Decrease) in Equity
Issuance of units in public offering, net of offering costs	$ 39,630			39,630
Issuance of units in public offering, net of offering costs (in units)	636
Distributions paid	$ (339,306)		(24,659)	(363,965)
Contributions from non-controlling interest			26,689	26,689
Sale of equity interest in a joint venture			11,319	11,319
Transfer of interest due to sale of joint venture	4,370		(4,370)
Share-based compensation activity	$ 4,270			4,270
Share-based compensation activity (in units)	200
Deferred income tax impact from changes in equity	$ (1,510)			(1,510)
Net (loss) income	(110,569)		29,698	(80,871)
Balance, Equity at Jun. 30, 2015	$ 4,355,128	$ 451,519	$ 1,022,154	$ 5,828,801
Balance, Equity (in units) at Jun. 30, 2015	187,389	11,973