Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2016 USD ($) Payment	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Home office and equipment [Abstract]
Accumulated depreciation of home office and equipment	$ 30,600,000	$ 26,100,000	$ 54,900,000
Depreciation expense of home office and equipment	$ 4,600,000	3,200,000	2,200,000
Minimum number of payments past due to be in default | Payment	2
Change in premium deficiency reserve	$ 0	23,751,000	24,710,000
Threshold period for amortization	1 year
Maximum age for qualified employees for both medical and dental benefits	65 years
Related party transaction amount	$ 0	$ 0	$ 0
Minimum
Home office and equipment [Abstract]
Estimated useful life	3 years
Award vesting period	1 year
Maximum
Home office and equipment [Abstract]
Estimated useful life	45 years
Award vesting period	3 years