Summary of Significant Accounting Policies - Schedule of Regulatory Assets and Liabilities (Parenthetical) (Detail) (USD $)	Dec. 31, 2013 FPU	Dec. 31, 2010 Parent	Dec. 31, 2009 Parent
Schedule Of Regulatory Assets And Liabilities [Line Items]
Premium paid by FPU for acquisition	$ 1,300,000
Premium paid for acquisition		$ 746,000	$ 34,200,000