Fair Value (Details 3) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Fair value by pricing source
Available-for-sale securities	$ 713,291	$ 599,941
Fair value measurements on a recurring basis
Fair value by pricing source
Available-for-sale securities	713,291	599,941
Total	717,703	604,467
Fair value measurements on a recurring basis | Fixed maturities
Fair value by pricing source
Available-for-sale securities	707,341	587,209
Fair value measurements on a recurring basis | Fixed maturities | Priced via pricing services
Fair value by pricing source
Available-for-sale securities	707,341
Fair value measurements on a recurring basis | Common stock
Fair value by pricing source
Available-for-sale securities	5,950	12,732
Fair value measurements on a recurring basis | Common stock | Priced via pricing services
Fair value by pricing source
Available-for-sale securities	5,950
Fair value measurements on a recurring basis | Real estate
Fair value by pricing source
Other investments	4,412	4,526
Fair value measurements on a recurring basis | Real estate | Priced via unobservable inputs
Fair value by pricing source
Other investments	4,412
Fair value measurements on a recurring basis | Level 1
Fair value by pricing source
Available-for-sale securities	5,950	12,732
Total	5,950	12,732
Fair value measurements on a recurring basis | Level 1 | Fixed maturities
Fair value by pricing source
Available-for-sale securities	0	0
Fair value measurements on a recurring basis | Level 1 | Fixed maturities | Priced via pricing services
Fair value by pricing source
Available-for-sale securities	0
Fair value measurements on a recurring basis | Level 1 | Common stock
Fair value by pricing source
Available-for-sale securities	5,950	12,732
Fair value measurements on a recurring basis | Level 1 | Common stock | Priced via pricing services
Fair value by pricing source
Available-for-sale securities	5,950
Fair value measurements on a recurring basis | Level 2
Fair value by pricing source
Available-for-sale securities	697,989	578,563
Total	697,989	578,563
Fair value measurements on a recurring basis | Level 2 | Fixed maturities
Fair value by pricing source
Available-for-sale securities	697,989	578,563
Fair value measurements on a recurring basis | Level 2 | Fixed maturities | Priced via pricing services
Fair value by pricing source
Available-for-sale securities	697,989
Fair value measurements on a recurring basis | Level 2 | Common stock
Fair value by pricing source
Available-for-sale securities	0	0
Fair value measurements on a recurring basis | Level 2 | Common stock | Priced via pricing services
Fair value by pricing source
Available-for-sale securities	0
Fair value measurements on a recurring basis | Level 3
Fair value by pricing source
Available-for-sale securities	9,352	8,646
Total	9,352	8,646
Fair value measurements on a recurring basis | Level 3 | Priced via broker quotes
Fair value by pricing source
Available-for-sale securities	9,400
Fair value measurements on a recurring basis | Level 3 | Fixed maturities
Fair value by pricing source
Available-for-sale securities	9,352	8,646
Fair value measurements on a recurring basis | Level 3 | Fixed maturities | Priced via pricing services
Fair value by pricing source
Available-for-sale securities	9,352
Fair value measurements on a recurring basis | Level 3 | Common stock
Fair value by pricing source
Available-for-sale securities	0	$ 0
Fair value measurements on a recurring basis | Level 3 | Common stock | Priced via pricing services
Fair value by pricing source
Available-for-sale securities	0
Fair value measurements on a nonrecurring basis
Fair value by pricing source
Total	$ 0