Employee Benefits (Net Periodic Benefit Costs) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Retirement Income Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 9,137	$ 8,530	$ 6,590
Interest cost	12,742	12,594	12,871
Expected return on plan assets	(17,108)	(14,443)	(14,095)
Amortization of:
Net loss	10,437	10,729	6,190
Prior service cost (benefit)	3	21	21
Net periodic benefit cost	15,211	17,431	11,577
Non-Qualified Retirement Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	190	299	260
Interest cost	872	963	1,116
Expected return on plan assets	0	0	0
Amortization of:
Net loss	661	627	354
Prior service cost (benefit)	94	94	94
Net periodic benefit cost	$ 1,817	$ 1,983	$ 1,824