Notes Payable (Details) (USD $)		12 Months Ended			12 Months Ended			12 Months Ended		0 Months Ended
	Dec. 31, 2013	Dec. 31, 2012 Notes Payable under Revolving Credit Agreement 2016 Credit Agreement [Member]	Dec. 31, 2013 Notes Payable under Revolving Credit Agreement 2016 Credit Agreement [Member]	Mar. 07, 2012 Notes Payable under Revolving Credit Agreement 2016 Credit Agreement [Member]	Dec. 31, 2011 Notes Payable under Revolving Credit Agreement Former Credit Agreement [Member]	Dec. 31, 2013 Notes Payable under Revolving Credit Agreement Former Credit Agreement [Member]	Mar. 07, 2012 Notes Payable under Revolving Credit Agreement Former Credit Agreement [Member]	Dec. 31, 2007 Senior Notes [Member] Senior Notes, 6% Due May 15, 2017 [Member]	Dec. 31, 2013 Senior Notes [Member] Senior Notes, 6% Due May 15, 2017 [Member]	Nov. 24, 2010 Senior Notes [Member] Senior Notes, 6% Due November 30, 2015 [Member]	Dec. 31, 2013 Senior Notes [Member] Senior Notes, 6% Due November 30, 2015 [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Length of Agreement		4 years
Line of Credit Facility, Maximum Borrowing Capacity			$ 225,000,000	$ 325,000,000		$ 245,000,000.0
Increase in Maximum Indebtedness Related to Advances from FHLB and Issuance of Surplus Notes	150,000,000
Federal Home Loan Bank, Advances, General Debt Obligations, Maximum Amount Available	250,000,000
Maximum Indebtedness, Issuance of Surplus Notes	100,000,000
Line of Credit Facility, Reduction of Borrowing Capacity			100,000,000
Line of Credit Facility, Amount Outstanding			0		0		0
Line of Credit Facility, Remaining Borrowing Capacity			225,000,000
Revolving Credit Agreement					95,000,000
Debt Instrument, Interest Rate, Stated Percentage									6.00%		6.00%
Debt Instrument, Face Amount								360,000,000		250,000,000
Proceeds from Debt, Net of Issuance Costs								$ 354,800,000		$ 247,800,000
Debt Instrument, Interest Rate, Effective Percentage								6.19%		6.21%