Long-Term Debt and Revolving Lines of Credit (Details) $ in Thousands		12 Months Ended
	Dec. 18, 2015 USD ($)	Dec. 31, 2015 USD ($) Facility Institution	Dec. 31, 2014 USD ($)
Debt Instrument [Line Items]
Long term debt		$ 201,250
Current maturities		23,000	$ 23,000
Total long-term debt		$ 178,250	201,250
Minimum percentage of aggregate principal balance on which entity must obtain interest rate protection		33.00%
Minimum days to obtain interest rate protection		90 days
Minimum time to maintain interest rate protection		3 years
Number of credit facilities | Facility		3
Number of years of interest-only payments		2 years
Number of additional farm credit institutions | Institution		16
Number of facilities included in credit agreement | Facility		3
Aggregate principal amount of incremental term loan facilities, maximum		$ 100,000
Derivative asset, fair value		$ 688	1,900
Percentage of principal amount of loan on which entity entered in pay fixed receive variable interest rate swap		76.00%
Derivative effective interest rate		2.25%
Derivative fixed interest rate		3.38%
Percentage of effective interest rate on portion of debt		1.13%
Compliance with financial covenants [Abstract]
Total Leverage Ratio, Actual		1.35
Debt Service Coverage Ratio, Actual		4.24
Equity to Assets Ratio, Actual		46.1
Total Leverage Ratio, Covenant Requirement		2.00
Debt Service Coverage Ratio, Covenant Requirement		2.50
Equity to Assets Ratio, Covenant Requirement		35.0
Aggregate maturities of long-term debt [Abstract]
2016		$ 23,000
2017		23,000
2018		23,000
2019		132,250
2020		0
Long term debt, Total		201,250
Accrued in anticipation of early 2014 distribution of patronage credit		$ 1,500
Percentage of patronage credit paid in cash		75.00%
Percentage of patronage credit paid in shares		25.00%
Credit Facility One [Member]
Debt Instrument [Line Items]
Term of credit facility	5 years
Maximum borrowing capacity	$ 75,000
CoBank Term Loan [Member]
Debt Instrument [Line Items]
Long term debt		$ 201,250	224,250
Interest rate		2.67%
Basis spread on variable rate		2.25%
Required periodic installments		$ 5,750
Expected final payment		$ 120,750
Maturity date		Sep. 30, 2019
Debt instrument, description of variable rate basis		30-day LIBOR
Trailing month basis of financial covenants		12 months
Compliance with financial covenants [Abstract]
Debt Service Coverage Ratio, Actual		2.50
Equity to Assets Ratio, Actual		0.35
Total Leverage Ratio, Covenant Requirement		2.00
Aggregate maturities of long-term debt [Abstract]
Long term debt, Total		$ 201,250	$ 224,250
CoBank Term Loan [Member] | Amendment date through December 31, 2013 [Member]
Debt Instrument [Line Items]
Basis spread on variable rate		0.42%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 50,000
Term Loan [Member] | Credit Facility Two [Member]
Debt Instrument [Line Items]
Term of credit facility	5 years
Maximum borrowing capacity	$ 485,000
Term Loan [Member] | Credit Facility Three [Member]
Debt Instrument [Line Items]
Term of credit facility	7 years
Maximum borrowing capacity	$ 400,000