Notes Payable (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Debt Instrument
Notes payable	$ 300,196	$ 317,912
Senior Notes due April 2025
Debt Instrument
Notes payable	148,419	148,311
Unamortized discount	1,581	1,689
FHLB notes
Debt Instrument
Notes payable	98,073	102,596
Unamortized premium	469	627
Insurance company note payable due March 2035
Debt Instrument
Notes payable		20,000
NLIC note payable due May 2033
Debt Instrument
Notes payable	10,000	10,000
NLIC note payable due September 2033
Debt Instrument
Notes payable	10,000	10,000
ASIC note payable due April 2034
Debt Instrument
Notes payable	7,500	7,500
Insurance company line of credit due December 31, 2017
Debt Instrument
Notes payable	3,000	3,000
Ventures Management line of credit due January 2018
Debt Instrument
Notes payable	$ 23,204	$ 16,505