Retirement and Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2011

Dec. 31, 2010

Retirement and Employee Benefit Plans [Abstract]

Changes in the plans' benefit obligations, fair value of assets, and funded status

			Other Postretirement
	Pension Benefits		Benefits
	2011	2010	2011	2010
	(in thousands)
Change in benefit obligations:
Benefit obligation at January 1	$       67,933	$       56,736	$         4,955	$         3,271
Service cost	9,323	7,096	1,354	1,089
Interest cost	3,671	3,249	252	195
Participant contributions	0	0	19	15
Actuarial loss	6,967	6,311	302	462
Benefits paid	(6,156)	(5,029)	(89)	(77)
Plan amendments	0	168	0	0
Settlements	0	(598)	0	0
Benefit obligation at December 31	$       81,738	$       67,933	$         6,793	$         4,955
			Other Postretirement
	Pension Benefits		Benefits
	2011	2010	2011	2010
	(in thousands)
Change in plan assets:
Fair value of plan assets at January 1	$       56,949	$       46,689	$                0	$                0
Actual return/(loss) on plan assets	4,717	6,276	0	0
Employer contributions	12,513	9,667	70	62
Participant contributions	0	0	19	15
Benefits paid	(6,156)	(5,029)	(89)	(77)
Settlements	0	(654)	0	0
Fair value of plan assets at December 31	$       68,023	$       56,949	$                0	$                0
Funded status of plans at December 31	$      (13,715)	$      (10,984)	$         (6,793)	$         (4,955)

Projected benefit obligation, accumulated benefit obligation and fair value of plan assets

	2011	2010
	(in thousands)
Projected benefit obligation	$          81,738	$          67,933
Accumulated benefit obligation	$          77,317	$          63,665
Fair value of plan assets	$          68,023	$          56,949

Pension and other postretirement benefit costs

				Other Postretirement
	Pension Benefits			Benefits
	2011	2010	2009	2011	2010	2009
	(in thousands)
Service cost	$    9,323	$    7,096	$    5,148	$     1,354	$     1,089	$        696
Interest cost	3,671	3,249	2,874	252	195	136
Expected return on plan assets	(4,398)	(3,503)	(2,809)	0	0	0
Amortization of transition obligation	0	0	0	64	65	65
Amortization of prior service cost	344	346	334	14	14	14
Amortization of net loss	856	806	846	11	21	7
Net periodic benefit cost	9,796	7,994	6,393	1,695	1,384	918
Settlements and curtailments	0	223	0	0	0	0
Total benefit cost	$    9,796	$    8,217	$    6,393	$     1,695	$     1,384	$        918

Amounts recognized in other comprehensive income

	Pension Benefits	Other Postretirement Benefits
	(in thousands)
Net actuarial loss arising during the year	$           (6,648)	$               (302)
Amortization of transition obligation	0	64
Amortization of prior service cost	344	14
Amortization of net loss	856	11
Tax effect	2,210	88
	$           (3,238)	$               (125)

Weighted average assumptions used in the measurement of benefit obligations

			Other Postretirement
	Pension Benefits		Benefits
	2011	2010	2011	2010
Discount rate	5.00%	5.50%	5.00%	5.50%
Rate of compensation increase	4.50%	4.50%	n/a	n/a

Weighted average assumptions used in the measurement of net periodic benefit cost

				Other Postretirement
	Pension Benefits			Benefits
	2011	2010	2009	2011	2010	2009
Discount rate	5.50%	5.75%	6.00%	5.50%	5.75%	6.00%
Expected return on plan assets	7.50%	7.50%	7.50%	n/a	n/a	n/a
Rate of compensation increase	4.50%	4.50%	4.50%	n/a	n/a	n/a

Measurement purposes following trend rates were assumed

	2011	2010
Health care cost trend assumed for next year	9%	9%
Rate to which the cost trend is assumed to decline	5%	5%
Year that the rate reaches the ultimate trend rate	2031	2030

One percentage point change in assumed health care cost trend rates

	1% Increase	1% Decrease
	(in thousands)
Effect on the total service and interest cost components	$       235	$      (196)
Effect on postretirement benefit obligation	$       940	$      (788)

Benefit payments, which reflect expected future service

	Pension Benefits	Other Postretirement Benefits
	(in thousands)
2012	$            3,894	$                150
2013	$            4,808	$                217
2014	$            6,310	$                322
2015	$            6,183	$                443
2016	$            7,908	$                657
Years 2017-2021	$          54,647	$             5,321

Plan assets allocation to any asset class falls outside of the specified range

	Pension Plan Asset Allocations
Asset category:	Target	Actual
Equity securities:
U.S. large cap growth equity	6%	6%
U.S. large cap value equity	6%	5%
U.S. large cap core equity	15%	16%
U.S. small cap equity	3%	3%
Non-U.S. equity	25%	25%
Emerging markets equity	5%	5%
Fixed income and cash and cash equivalents	40%	40%
Total	100%	100%

Fair Value Measurement Of Pension Plan Assets [Table]

		Quoted Prices in Active Markets for Identical Assets	Significant Observable Inputs	Significant Unobservable Inputs
Asset category:	Total	(Level 1)	(Level 2)	(Level 3)
	(in thousands)
Equity securities:
U.S. large cap growth equity (1)	$         3,792	$         3,792	$               0	$               0
U.S. large cap value equity (2)	3,689	3,689	0	0
U.S. large cap core equity (3)	10,849	0	10,849	0
U.S. small cap equity (4)	2,201	2,201	0	0
Non-U.S. equity (5)	16,719	16,719	0	0
Emerging markets equity (6)	3,377	0	3,377	0
Fixed income (7)	25,192	0	25,192	0
Cash and cash equivalents	2,204	2,204	0	0
Total	$       68,023	$       28,605	$               39,418	$               0

		Quoted Prices in Active Markets for Identical Assets	Significant Observable Inputs	Significant Unobservable Inputs
Asset category:	Total	(Level 1)	(Level 2)	(Level 3)
	(in thousands)
Equity securities:
Large cap growth equity (1)	$         5,937	$         5,937	$               0	$               0
Large cap value equity (2)	5,838	5,838	0	0
Large cap core equity (3)	8,062	8,062	0	0
Small cap equity (4)	6,662	6,662	0	0
International equity (5)	8,333	8,333	0	0
Fixed income (6)	18,539	18,539	0	0
Cash and cash equivalents	3,578	3,578	0	0
Total	$       56,949	$       56,949	$               0	$               0