Employee Benefit Plans Schedule of Amounts Recognized in Other Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Changes in AOCL [Roll Forward]
Accumulated other comprehensive loss (Beginning Bal)		$ (96,350)
Amortization of prior service credit	[1]	(973)	$ (928)
Amortization of actuarial loss	[1]	1,401	1,572
Accumulated other comprehensive loss (Ending Bal)		(108,012)
Pension Plan [Member]
Changes in AOCL [Roll Forward]
Accumulated other comprehensive loss (Beginning Bal)		(62,279)	(63,257)
Amortization of prior service credit		(45)	0
Amortization of actuarial loss		1,217	1,347
Accumulated other comprehensive loss (Ending Bal)		(61,107)	(61,910)
Other Postretirement Benefit Plan [Member]
Changes in AOCL [Roll Forward]
Accumulated other comprehensive loss (Beginning Bal)		(3,945)	(1,696)
Amortization of prior service credit		(928)	(928)
Amortization of actuarial loss		184	225
Accumulated other comprehensive loss (Ending Bal)		$ (4,689)	$ (2,399)

[1] See Note 6–Employee Benefit Plans for details of the changes in employee benefit plan assets and benefit obligations recognized in AOCL.