Employee Benefit Plans Employee Benefit Plans (Weighted average interest rate assumptions) (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Supplemental Executive Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.80%	4.22%
Rate of compensation increase	4.00%	4.00%
Post-Retirement Medical Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.05%	4.31%
Initial health care cost trend	6.75%	7.00%
Ultimate health care cost trend	5.00%	5.00%
Defined Benefit Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.20%	4.55%
Rate of compensation increase	4.47%	4.47%