Retirement and Employee Benefit Plans (Amounts Recognized in Other Comprehensive Income) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Tax effect	$ (2,700)	$ (2,000)	$ (200)
Pension Benefits [Member]
Net actuarial loss arising during the year	(6,648)
Amortization of transition obligation	0
Amortization of prior service cost	344
Amortization of net loss	856
Tax effect	2,210
Total	(3,238)
Other Postretirement Benefits [Member]
Net actuarial loss arising during the year	(302)
Amortization of transition obligation	64
Amortization of prior service cost	14
Amortization of net loss	11
Tax effect	88
Total	$ (125)