Real Estate Sales - AgReserves Sales (Details) - USD ($)		1 Months Ended	12 Months Ended
	Mar. 05, 2014	Apr. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Other operating expenses			$ 33,426,000	$ 26,128,000	$ 27,855,000
Investments held by special purpose entities	$ 203,500,000		208,785,000	209,857,000
Debt principal amount		$ 180,000,000
Debt interest rate		4.75%
Proceeds from monetization		$ 165,000,000
Cost of monetization		$ 15,000,000
Expected amount to receive upon maturity of note after payment of note and any other liabilities			20,000,000
Administrative costs associated with special purpose entities			$ 0	3,746,000	0
Percent Ownership in Special Purpose Entity			0.00%
Senior Notes held by special purpose entity			$ 177,445,000	177,341,000
Interest income from investments in special purpose entities			8,217,000	6,116,000	0
Interest expense and amortization of discount and issuance costs for Senior Notes issued by special purpose entity			(8,755,000)	(6,584,000)	$ 0
Subsidiaries | Notes Receivable
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Issue price of Senior Secured Notes		98.483%
Special Purpose Entities
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Debt discount and issuance costs		$ 4,300,000
Investments Contributed to Special Purpose Entity by the Company		$ 7,000,000
Assets Held by Special Purpose Entities			213,500,000
Liabilities Held by Special Purpose Entities			180,300,000
U.S. Treasury securities			8,500,000
Cash			300,000
Deferred issuance costs			1,400,000
Senior Notes held by special purpose entity			177,400,000
Debt unamortized discount			2,500,000
Accrued interest expense for Senior Notes held by special purpose entity			$ 2,850,000	2,852,000
Held-To-Maturity Security, Term			14 years
Held-to-maturity Securities, Debt Maturities, within One Year, Net Carrying Amount			$ 800,000
Held-to-maturity Securities, Debt Maturities, Year Two Through Five, Fair Value			3,600,000
Held-to-maturity Securities, Debt Maturities, after Five Through Ten Years, Net Carrying Amount			3,000,000
Held-to-maturity Securities, Debt Maturities, after Ten Years, Net Carrying Amount			$ 1,100,000
Special Purpose Entities | Notes Receivable
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Debt interest rate			4.006%
Buyer Special Purpose Entity
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Time Deposits			$ 200,000,000
Accrued Investment Income Receivable			$ 3,300,000
AgReserves Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration received for real estate sale	562,000,000
Pre-tax income on real estate sale	511,100,000
Other operating expenses				$ 1,200,000
Cash proceeds from sale of real estate	358,500,000
Notes received in sale of real estate	$ 200,000,000
Maturity of notes receivables	15 years