Employee Benefit Plans Schedule of Amounts Recognized in Other Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Changes in AOCL [Roll Forward]
Accumulated other comprehensive loss (Beginning Bal)				$ (81,540)
Amortization of prior service credit	[1]	$ (928)	$ (928)	(2,784)	$ (2,751)
Amortization of actuarial loss	[1]	1,798	985	5,393	3,001
Settlement cost	[1]	0	30	0	1,599
Accumulated other comprehensive loss (Ending Bal)		(94,894)		(94,894)
Pension Plan [Member]
Changes in AOCL [Roll Forward]
Accumulated other comprehensive loss (Beginning Bal)		(60,104)	(33,023)	(63,257)	(36,184)
Amortization of prior service credit		0	0	0	33
Amortization of actuarial loss		1,577	756	4,730	2,315
Settlement cost		0	30	0	1,599
Accumulated other comprehensive loss (Ending Bal)		(58,527)	(32,237)	(58,527)	(32,237)
Other Postretirement Benefit Plan [Member]
Changes in AOCL [Roll Forward]
Accumulated other comprehensive loss (Beginning Bal)		(3,110)	1,654	(1,696)	3,053
Amortization of prior service credit		(928)	(928)	(2,784)	(2,784)
Amortization of actuarial loss		221	229	663	686
Settlement cost		0	0	0	0
Accumulated other comprehensive loss (Ending Bal)		$ (3,817)	$ 955	$ (3,817)	$ 955

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