Capital Requirements - Dividends to Parent (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Cash dividend
Dividends paid to parent company	$ 16,000,000	$ 18,000,000
Retained earnings	62,136,000	$ 52,527,000
HCC (Parent)
Cash dividend
Cash dividend available	$ 17,260,000