Pension Plan and Employee Benefits, Amounts Recognized in Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 358,128	$ 387,776
Amounts recognized in other comprehensive income [Abstract]
Net actuarial (gain) loss occurring during year	(49,978)	32,177
Prior service cost occurring during year	0	0
Net actuarial loss (gain) amortized during year	13,218	8,346
Transition obligation (asset) amortized during year	0	0
Prior service cost (credit) amortized during year	(71)	(71)
Amounts in accumulated other comprehensive income to be recognized in next fiscal year [Abstract]
Net actuarial loss (gain)	6,404
Transition obligation (asset)	0
Prior service cost (credit)	(71)
Amounts in accumulated other comprehensive income [Abstract]
Net actuarial loss (gain)	93,821	157,017
Transition obligation (asset)	0	0
Prior service cost (credit)	(488)	(559)
Other Benefits [Member]
Amounts recognized in other comprehensive income [Abstract]
Net actuarial (gain) loss occurring during year	(1,768)	2,461
Prior service cost occurring during year	601	0
Net actuarial loss (gain) amortized during year	1,131	1,479
Transition obligation (asset) amortized during year	20	20
Prior service cost (credit) amortized during year	0	0
Amounts in accumulated other comprehensive income to be recognized in next fiscal year [Abstract]
Net actuarial loss (gain)	854
Transition obligation (asset)	16
Prior service cost (credit)	119
Amounts in accumulated other comprehensive income [Abstract]
Net actuarial loss (gain)	10,703	13,602
Transition obligation (asset)	16	35
Prior service cost (credit)	601	0
SERP Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	53,046	53,350
Amounts recognized in other comprehensive income [Abstract]
Net actuarial (gain) loss occurring during year	(3,477)	11,651
Net actuarial loss (gain) amortized during year	2,305	1,764
Prior service cost (credit) amortized during year	54	54
Amounts in accumulated other comprehensive income to be recognized in next fiscal year [Abstract]
Net actuarial loss (gain)	1,396
Prior service cost (credit)	54
Amounts in accumulated other comprehensive income [Abstract]
Net actuarial loss (gain)	19,663	25,444
Prior service cost (credit)	$ 227	$ 280