Retirement and Other Employee Benefits (Components of Net Periodic Benefit Cost) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Qualified Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 7,966		$ 7,832		$ 24,366		$ 26,432
Interest cost	9,521		8,867		27,821		24,017
Expected return on plan assets	(12,427)		(11,036)		(37,127)		(33,186)
Amortization of prior service cost	0		4		0		4
Amortization of net loss (gain)	1,792		3,801		6,342		17,451
Curtailment/settlement charge	0		0		0		0
Net periodic benefit cost	6,852		9,468		21,402		34,718
Non-Qualified Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	1,139	[1]	1,008	[1]	3,139	[1]	3,308	[1]
Interest cost	1,636	[1]	1,480	[1]	4,636	[1]	3,880	[1]
Expected return on plan assets	0	[1]	0	[1]	0	[1]	0	[1]
Amortization of prior service cost	218	[1]	249	[1]	618	[1]	599	[1]
Amortization of net loss (gain)	969	[1]	1,182	[1]	2,819	[1]	4,382	[1]
Curtailment/settlement charge	436	[1]	0		436	[1]	0
Net periodic benefit cost	4,398	[1]	3,919	[1]	11,648	[1]	12,169	[1]
Retirement Health Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	494		581		1,694		2,281
Interest cost	959		911		2,909		2,561
Expected return on plan assets	(766)		(799)		(2,316)		(2,199)
Amortization of prior service cost	(242)		(241)		(692)		(691)
Amortization of net loss (gain)	(208)		0		(308)		0
Curtailment/settlement charge	0		0		0		0
Net periodic benefit cost	$ 237		$ 452		$ 1,287		$ 1,952

[1] The Company’s nonqualified plan is unfunded.