Retirement And Other Employee Benefits (Summary Of Pension Benefits And Retirement Health Benefits Plans) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Projected benefit obligation at beginning of year	$ (1,064,042)	$ (905,943)
Projected benefit obligation at end of year	(1,018,594)	(1,064,042)	$ (905,943)
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	879,211	786,750
Fair value of plan assets at end of year	832,686	879,211	786,750
Projected benefit obligation at beginning of year	(185,908)	(184,831)	(119,193)
Pension Benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Projected benefit obligation at beginning of year	(1,064,042)	(905,943)	(956,172)
Service cost	(41,989)	(36,609)	(38,580)
Interest cost	(41,766)	(43,613)	(38,243)
Actuarial (loss) gain, including curtailments and settlements	52,201	(127,940)	89,029
Benefits paid	77,002	50,063	38,023
Projected benefit obligation at end of year	(1,018,594)	(1,064,042)	(905,943)
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	879,211	786,750	704,976
Actual return on plan assets	(5,458)	102,628	64,641
Employer contributions	37,664	41,384	56,217
Benefits paid (including administrative expenses)	(78,731)	(51,551)	(39,084)
Fair value of plan assets at end of year	832,686	879,211	786,750
Projected benefit obligation at beginning of year	(185,908)	(184,831)	(119,193)
Retirement Health Benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Projected benefit obligation at beginning of year	(96,306)	(79,046)	(86,237)
Service cost	(2,429)	(2,188)	(2,863)
Interest cost	(3,834)	(3,868)	(3,473)
Actuarial (loss) gain, including curtailments and settlements	5,938	(13,910)	11,213
Benefits paid	3,121	2,706	2,314
Projected benefit obligation at end of year	(93,510)	(96,306)	(79,046)
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	50,068	46,971	45,651
Actual return on plan assets	(291)	5,403	3,234
Employer contributions	200	400	400
Benefits paid (including administrative expenses)	(3,121)	(2,706)	(2,314)
Fair value of plan assets at end of year	46,856	50,068	46,971
Projected benefit obligation at beginning of year	$ (46,654)	$ (46,238)	$ (32,075)