Minimum Lease Payment Obligations under Operating Leases with Terms in Excess of One Year (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011
Schedule of Operating Leases [Line Items]
2012	$ 11,602
2013	11,996
2014	10,665
2015	8,774
2016	9,018
Thereafter	399,196
Total	451,251
Office space and other
Schedule of Operating Leases [Line Items]
2012	2,443
2013	2,589
2014	2,690
2015	2,768
2016	2,869
Thereafter	14,247
Total	27,606
Pumping and compression equipment
Schedule of Operating Leases [Line Items]
2012	3,487	[1]
2013	3,608	[1]
2014	2,093	[1]
Total	9,188	[1]
Land Leases
Schedule of Operating Leases [Line Items]
2012	5,672	[2]
2013	5,799	[2]
2014	5,882	[2]
2015	6,006	[2]
2016	6,149	[2]
Thereafter	384,949	[2]
Total	$ 414,457	[2]

[1] Includes BORCO facility leases for tugboats and a barge in our International Operations segment.

[2] Includes leases the for inland dock and seabed in connection with our operations in the International Operations segment and subsurface underground gas storage rights and surface rights in connection with our operations in the Natural Gas Storage segment. We may cancel these leases if the storage reservoir is not used for underground storage of natural gas or the removal or injection thereof for a continuous period of two consecutive years. Rental expense associated with these leases, which is being recognized on a straight-line basis over 44 years, was approximately $7.1 million, $7.1 million and $7.4 million for the years ended December 31, 2011, 2010 and 2009, respectively. At December 31, 2011 and 2010, the balance of our Natural Gas Storage segment deferred lease liability increased by $4.1 million and $4.2 million, respectively, to $17.5 million and $13.3 million, respectively in the years ended December 31, 2011 and 2010. We estimate that the deferred lease liability will continue to increase through 2032, at which time our deferred lease liability is estimated to be approximately $64.7 million. Our deferred lease liability will then be reduced over the remaining 19 years of the lease, since the expected annual lease payments will exceed the amount of lease expense.