Pension and Other Post-Retirement Benefit Plans (Funded Status) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Pension Plans [Member]
Change in benefit obligation [Roll Forward]
Service cost	$ 0	$ 0	$ 0	$ 0
Interest cost	8,646	9,879	25,938	29,637
Change in plan assets [Roll Forward]
Employer contributions	5,297		6,232
Post-Retirement Healthcare Plans [Member]
Change in benefit obligation [Roll Forward]
Service cost	44	60	132	180
Interest cost	$ 48	$ 71	$ 144	$ 213