Deferred Policy Acquisition Costs and Value of Business Acquired (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
DPAC [Roll Forward]      
Balance, beginning of period $ 161,731 $ 151,756 $ 140,928
Additions 47,742 48,599 48,723
VOBA interest 0 0 0
Amortization (40,848) (38,624) (37,895)
Net change 6,894 9,975 10,828
Balance, end of period 168,625 161,731 151,756
VOBA [Roll Forward]      
Balance, beginning of period 28,917 32,344 36,361
Additions 0 0 0
VOBA interest 1,381 1,543 1,726
Amortization (4,136) (4,970) (5,743)
Net change (2,755) (3,427) (4,017)
Balance, end of period 26,162 28,917 32,344
TOTAL [Roll Forward]      
Balance, beginning of period 190,648 184,100 177,289
Additions 47,742 48,599 48,723
VOBA interest 1,381 1,543 1,726
Amortization (44,984) (43,594) (43,638)
Net change 4,139 6,548 6,811
Balance, end of period $ 194,787 $ 190,648 $ 184,100
VOBA interest rate 5.15% 5.15% 5.17%
Portion of DPAC and VOBA amortization recorded within unrealized gains on securities component of other comprehensive income $ 3,147    
Value of business acquired future amortization expense [Abstract]      
2017 3,582    
2018 2,597    
2019 2,279    
2020 2,009    
2021 $ 2,075