Employee Benefit Plans - Defined Benefit Plans - Weighted-average assumptions (Details) - The Bank - Cash Balance Plan	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Weighted-average assumptions for net periodic benefit cost as of
Discount rate	3.80%	3.60%	4.40%
Expected return on plan assets	7.50%	7.50%	7.50%
Rate of compensation increase	3.00%	3.00%	3.00%