Retirement Plan 4 (Details) (Net of Medicare Subsidy [Member], USD $) In Thousands, unless otherwise specified	Dec. 31, 2011
Net of Medicare Subsidy [Member]
Estimated Future Pension Benefit Payments [Line Items]
For the first year	$ 29,527
For the second year	27,887
For the third year	26,583
For the fourth year	25,245
For the fifth year	24,272
For the years ending 12/31/15-12/31/19	105,199
Expected Future Benefit Payments Total	$ 238,713