Long-Term Debt - Narrative (Details) (USD $)			6 Months Ended
	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2014 Six Point Zero Percent Senior Notes Due On June Fifteen Two Thousand And Seventeen [Member]	May 08, 2013 Six Point Zero Percent Senior Notes Due On June Fifteen Two Thousand And Seventeen [Member]	Jun. 30, 2014 Miles Kimball [Member]	Dec. 31, 2013 Miles Kimball [Member]	Jun. 30, 2014 Short Term Bond Mutual Funds [Member]	Dec. 31, 2013 Short Term Bond Mutual Funds [Member]	Jun. 30, 2014 Certificates of Deposit [Member]	Dec. 31, 2013 Certificates of Deposit [Member]
Debt Instrument [Line Items]
Available-for-sale Securities	$ 26,059,000	$ 10,231,000					$ 24,034,000	$ 7,985,000	$ 1,663,000	$ 1,634,000
Note issuance date			May 10, 2013
Senior notes issued				50,000,000
Interest rate of Senior Notes				6.00%
Maturity date of long-term debt outstanding			Jun. 30, 2017
Long-term debt outstanding					5,200,000	5,500,000
Long-term debt fixed interest rate					7.89%
Amount available under uncommitted bank facility to be used for letters of credit	2,400,000
Letters of credit outstanding, amount	$ 1,100,000