Long-Term Debt (Narrative) (Details) (Prosperity Bank [Member], USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 16, 2015	Mar. 15, 2015	Dec. 31, 2014
Prosperity Bank [Member]
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity	$ 40,000,000
Borrowing base			14,300,000
Decreased borrowing base		7,800,000
Rate above prime	0.50%
Credit facility maturity date	Jan. 27, 2017
Loans and letters of credit amount outstanding	$ 843,000			$ 734,000