Capital Ratios (Details) - USD ($)		6 Months Ended
	Jan. 01, 2015	Jun. 30, 2017	Dec. 31, 2016	Jan. 01, 2016	Dec. 31, 2015	Jul. 31, 2013
CET 1 ratio		16.98%	16.95%
Tier 1 capital (to Average Assets), Actual Ratio (as a percent)		14.29%	13.91%
Tier 1 capital (to Risk Weighted Assets), Actual Ratio (as a percent)		18.66%	18.68%			6.00%
Total Capital (to Risk Weighted Assets), Actual Ratio (as a percent)		19.44%	19.47%
Total Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Ratio (as a percent)				0.625%	2.50%
Term of mandatory compliance	4 years
Percentage of capital securities issued by trust qualifying as Tier I capital, maximum		25.00%
Percentage of capital securities issued by trust qualifying as Tier II capital, minimum		25.00%
Capital securities issued by the trust, qualifying as Tier I capital		$ 160,416,000	$ 160,416,000
Minimum
CET 1 ratio		7.00%
Tier 1 capital (to Risk Weighted Assets), Actual Ratio (as a percent)					4.50%	4.00%