Employee Benefit Plans Employee Benefit Plan (Amount in AOCI not yet realized) (Details) $ in Thousands	Dec. 31, 2016 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Net gain (loss), gross	$ (128,624)
Net prior service (cost) credit, Gross	(1,076)
Amounts in accumulated other comprehensive income (loss) that have not yet been recognized as components of net periodic benefit cost, Gross	(129,700)
Net gain (loss), Net of tax	(83,606)
Net prior service (cost) credit, Net of tax	(699)
Amounts in accumulated other comprehensive income (loss) that have not yet been recognized as components of net periodic benefit cost, Net of tax	(84,305)
Defined Benefit Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Net gain (loss), gross	(133,055)
Net prior service (cost) credit, Gross	0
Amounts in accumulated other comprehensive income (loss) that have not yet been recognized as components of net periodic benefit cost, Gross	(133,055)
Net gain (loss), Net of tax	(86,486)
Net prior service (cost) credit, Net of tax	0
Amounts in accumulated other comprehensive income (loss) that have not yet been recognized as components of net periodic benefit cost, Net of tax	(86,486)
Post-Retirement Medical Plan
Defined Benefit Plan Disclosure [Line Items]
Net gain (loss), gross	5,091
Net prior service (cost) credit, Gross	624
Amounts in accumulated other comprehensive income (loss) that have not yet been recognized as components of net periodic benefit cost, Gross	5,715
Net gain (loss), Net of tax	3,309
Net prior service (cost) credit, Net of tax	406
Amounts in accumulated other comprehensive income (loss) that have not yet been recognized as components of net periodic benefit cost, Net of tax	3,715
Supplemental Executive Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Net gain (loss), gross	(660)
Net prior service (cost) credit, Gross	(1,700)
Amounts in accumulated other comprehensive income (loss) that have not yet been recognized as components of net periodic benefit cost, Gross	(2,360)
Net gain (loss), Net of tax	(429)
Net prior service (cost) credit, Net of tax	(1,105)
Amounts in accumulated other comprehensive income (loss) that have not yet been recognized as components of net periodic benefit cost, Net of tax	$ (1,534)