Employee Benefit Plans Employee Benefit Plans (Weighted average interest rate assumptions - net periodic benefits) (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Supplemental Executive Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.22%	3.99%
Rate of compensation increase	4.00%	4.00%
Post-Retirement Medical Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.31%	3.94%
Initial health care cost trend	7.00%	6.50%
Ultimate health care cost trend	5.00%	5.00%
Defined Benefit Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.55%	4.17%
Expected return on plan assets	6.00%	6.50%
Rate of compensation increase	4.47%	4.47%