Pension and Other Post-Employment Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended	3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014 Pension Benefits	Mar. 31, 2013 Pension Benefits	Mar. 31, 2014 Other Benefits	Mar. 31, 2013 Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Amendments	$ 142	$ 11,600
Components of net periodic benefit cost
Service cost			1,075	1,318	48	93
Interest cost			2,812	2,699	283	425
Expected return on plan assets			(3,781)	(3,890)	0	0
Amortization of net actuarial losses	(1,686)		1,499	1,992	187	355
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)			0	0	(360)	0
Total net periodic benefit cost			$ 1,605	$ 2,119	$ 158	$ 873