Unaudited Summarized Pro Forma Consolidated Statements of Operations Assuming BORCO Acquisition Occurred (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2010		Sep. 30, 2010		Jun. 30, 2010		Mar. 31, 2010		Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Business Acquisition, Pro Forma Information [Line Items]
Revenues																	$ 4,759,610		$ 3,151,268		$ 1,770,372
Pro forma revenue																	4,768,032		3,344,388
Pro forma net income																	117,895		237,408
Net income (loss)	59,687	[1]	(109,700)	[1]	92,021	[1]	66,493	[1]	8,362	[2]	11,941	[2]	11,507	[2]	11,270	[2]	108,501	[1]	43,080	[2]	49,594
As reported
Business Acquisition, Pro Forma Information [Line Items]
Revenues																	4,759,610		3,151,268
Net income (loss)																	114,664		201,008
Restatement Adjustment
Business Acquisition, Pro Forma Information [Line Items]
Revenues																	8,422		193,120
Net income (loss)																	$ 3,231		$ 36,400

[1] The second quarter of 2011 includes a gain of $34.1 million, and the fourth quarter of 2011 includes subsequent dividend income of $0.6 million related to the sale of our equity interest in WT LPG (see Note 3). The third quarter of 2011 includes a $169.6 million goodwill impairment expense associated with the Natural Gas Storage segment (see Note 9).

[2] The fourth quarter of 2010 includes $21.1 million of non-cash compensation expense related to the modification of an equity compensation plan (see Note 18).