Schedule II - Valuation and Qualifying Accounts (Detail) - Table of Valuation and Qualifying Accounts (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2012 Includes Allowance of Doubtful Accounts from Acquisition of BIP [Member]
Balance at Beginning of Period	$ 143		$ 162	[1]
Deductions	31	[2]	18	[2]
Balance at End of Period	57		216
(Recovered From)/Charged to Costs and Expenses	$ (55)		$ 72

[1] Includes $105,000 of allowance for doubtful accounts related to acquisition of BIP (see Note 13 to the consolidated financial statements - Purchase of Interests in Subsidiaries)

[2] Uncollectible accounts written off, net of recoveries