Employee Benefit Plans Employee Benefit Plans (Amounts in AOCI expected to be realized) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Net gain (loss), Gross	$ (8,535)
Net prior service (cost) credit, Gross	(48)
Amounts in accumulated other comprehensive income (loss) that are expected to be recognized as components of net periodic benefit costs during the next fiscal year, Gross	(8,583)
Net gain (loss), Net of tax	(5,547)
Net prior service (cost) credit, Net of tax	(32)
Amounts in accumulated other comprehensive income (loss) that are expected to be recognized as components of net periodic benefit costs during the next fiscal year, Net of tax	(5,579)
Defined Benefit Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Net gain (loss), Gross	(8,799)
Net prior service (cost) credit, Gross	0
Amounts in accumulated other comprehensive income (loss) that are expected to be recognized as components of net periodic benefit costs during the next fiscal year, Gross	(8,799)
Net gain (loss), Net of tax	(5,719)
Net prior service (cost) credit, Net of tax	0
Amounts in accumulated other comprehensive income (loss) that are expected to be recognized as components of net periodic benefit costs during the next fiscal year, Net of tax	(5,719)
Post-Retirement Medical Plan
Defined Benefit Plan Disclosure [Line Items]
Net gain (loss), Gross	210
Net prior service (cost) credit, Gross	453
Amounts in accumulated other comprehensive income (loss) that are expected to be recognized as components of net periodic benefit costs during the next fiscal year, Gross	663
Net gain (loss), Net of tax	137
Net prior service (cost) credit, Net of tax	294
Amounts in accumulated other comprehensive income (loss) that are expected to be recognized as components of net periodic benefit costs during the next fiscal year, Net of tax	431
Supplemental Executive Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Net gain (loss), Gross	54
Net prior service (cost) credit, Gross	(501)
Amounts in accumulated other comprehensive income (loss) that are expected to be recognized as components of net periodic benefit costs during the next fiscal year, Gross	(447)
Net gain (loss), Net of tax	35
Net prior service (cost) credit, Net of tax	(326)
Amounts in accumulated other comprehensive income (loss) that are expected to be recognized as components of net periodic benefit costs during the next fiscal year, Net of tax	$ (291)