Employee Benefit Plans Unrecognized loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive loss	$ (17,722)	$ (37,341)	$ 5,675
Unrecognized gains arising in current year	4,680	(13,168)	8,369
Accumulated other comprehensive loss	(22,017)	(17,722)	(37,341)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive loss	(22,505)	(8,801)	(18,482)
Accumulated other comprehensive loss	(15,961)	(22,505)	(8,801)
Pension Plans | Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss) [Member]
Gross of tax
AOCI before Tax, Attributable to Parent	38,082	16,161
Reclass adjustment for postretirement plan gain included in net income	(3,127)	(974)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, before Tax	(4,559)	22,895
AOCI before Tax, Attributable to Parent	30,396	38,082	16,161
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive loss	24,754	10,505
Recognized component of periodic pension cost	(2,033)	(633)
Unrecognized gains arising in current year	(2,963)	14,882
Accumulated other comprehensive loss	19,758	24,754	10,505
Other Postretirement Benefit Plans | Accumulated Defined Benefit Plans Adjustment, Net Prior Service Cost [Member]
Gross of tax
AOCI before Tax, Attributable to Parent	(3,123)	(1,484)
Reclass adjustment for postretirement plan gain included in net income	258	32
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, before Tax	(2,469)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Prior to Curtailment, before Tax		0
Other Comprehensive Income (Loss), Finalization of Pension and Other Postretirement Benefit Plan Valuation, before Tax		1,452
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, After Curtailment, before Tax		235
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, After Curtailment, before Tax		(3,358)
AOCI before Tax, Attributable to Parent	(5,334)	(3,123)	(1,484)
Other Postretirement Benefit Plans | Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss) [Member]
Gross of tax
AOCI before Tax, Attributable to Parent	(336)	(1,137)
Reclass adjustment for postretirement plan gain included in net income	0	10
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, before Tax	(172)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Prior to Curtailment, before Tax		(313)
Other Comprehensive Income (Loss), Finalization of Pension and Other Postretirement Benefit Plan Valuation, before Tax		0
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, After Curtailment, before Tax		70
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, After Curtailment, before Tax		1,034
AOCI before Tax, Attributable to Parent	(508)	(336)	(1,137)
Other Postretirement Benefit Plans | Accumulated Defined Benefit Plans Adjustment [Member]
Gross of tax
AOCI before Tax, Attributable to Parent	(3,459)	(2,621)
Reclass adjustment for postretirement plan gain included in net income	258	42
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, before Tax	(2,641)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Prior to Curtailment, before Tax		(313)
Other Comprehensive Income (Loss), Finalization of Pension and Other Postretirement Benefit Plan Valuation, before Tax		1,452
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, After Curtailment, before Tax		305
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, After Curtailment, before Tax		(2,324)
AOCI before Tax, Attributable to Parent	(5,842)	(3,459)	(2,621)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive loss	(2,249)	(1,704)
Recognized component of periodic pension cost	168
Unrecognized gains arising in current year	(1,717)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Prior to Curtailment, Net of Tax		26
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Prior to Curtailment, Net of Tax		(203)
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Net of Tax		944
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, After Curtailment, Net of Tax		199
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, After Curtailment, Net of Tax		(1,511)
Accumulated other comprehensive loss	$ (3,798)	$ (2,249)	$ (1,704)