Employee Benefit Plans (Amounts Recognized Accumlated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss), before Income Taxes [Roll Forward]
Accumulated other comprehensive income (loss)	$ (34,319)	$ (29,899)
Amortization of gain (loss)	1,780	4,200
Net gain arising during the year	(3,064)	(8,620)	$ (4,698)
Accumulated other comprehensive income (loss)	(35,603)	(34,319)	(29,899)
Pension Benefits
Accumulated Other Comprehensive Income (Loss), before Income Taxes [Roll Forward]
Accumulated other comprehensive income (loss)	(35,258)	(30,481)
Amortization of gain (loss)	1,855	4,297
Net gain arising during the year	(2,511)	(9,074)
Accumulated other comprehensive income (loss)	(35,914)	(35,258)	(30,481)
Other Postretirement Benefits
Accumulated Other Comprehensive Income (Loss), before Income Taxes [Roll Forward]
Accumulated other comprehensive income (loss)	939	582
Amortization of gain (loss)	(75)	(97)
Net gain arising during the year	(553)	454
Accumulated other comprehensive income (loss)	$ 311	$ 939	$ 582