Income Taxes (Details 2) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Other employee benefits	$ 19,106	$ 19,945
Pension and other postretirement benefits	65,241	48,897
Allowance for management fee returned on cancelled policies	4,795	4,375
Other	81	546
Total deferred tax assets	89,223	73,763
Deferred tax liabilities:
Depreciation	18,493	17,843
Prepaid expenses	8,120	6,929
Limited partnerships	5,597	5,822
Unrealized gains on investments	1,657	1,360
Other	1,467	1,123
Total deferred tax liabilities	35,334	33,077
Net deferred tax asset	$ 53,889	$ 40,686