Employee Benefit Plans Multiemployer Pension Plan (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Multiemployer Plans [Line Items]
Multiemployer plan red zone status funded percentage, maximum	65.00%
Multiemployer plan yellow zone status funded percentage, minimum	65.00%
Mulitiemployer plan yellow status funded percentage, maximum	80.00%
Multiemployer plan green zone status funded percentage, minimum	80.00%
Multiemployer Plans, Pension [Member]
Multiemployer Plans [Line Items]
Multiemployer Plan, Period Contributions	$ 29,158	$ 30,276	$ 32,479
Multiemployer Plans, Postretirement Benefit [Member]
Multiemployer Plans [Line Items]
Multiemployer Plan, Period Contributions	24,000	24,700	28,900
Multiemployer Plans, Defined Contribution [Member]
Multiemployer Plans [Line Items]
Multiemployer Plan, Period Contributions	15,300	15,400	16,400
Edison Pension Plan [Member]
Multiemployer Plans [Line Items]
Multiemployer Plans, Surcharge	no
Multiemployer Plans, Collective-Bargaining Arrangement, Expiration Date	Dec. 31, 2012
Edison Pension Plan [Member] | Multiemployer Plans, Pension [Member]
Multiemployer Plans [Line Items]
Entity Tax Identification Number	936061681
Multiemployer Plan Number	001
Multiemployer Plans, Certified Zone Status	green	green
Multiemployer Plans, Funding Improvement Plan and Rehabilitation Plan	no
Multiemployer Plan, Period Contributions	2,700	1,933	1,627
IBEW Local 38 Pension Plan [Member]
Multiemployer Plans [Line Items]
Multiemployer Plans, Surcharge	no
IBEW Local 38 Pension Plan [Member] | Multiemployer Plans, Pension [Member]
Multiemployer Plans [Line Items]
Entity Tax Identification Number	346574238
Multiemployer Plan Number	001
Multiemployer Plans, Certified Zone Status	yellow	yellow
Multiemployer Plans, Certified Zone Status, Date	Apr. 30, 2011	Apr. 30, 2010
Multiemployer Plans, Funding Improvement Plan and Rehabilitation Plan	implemented
Multiemployer Plan, Period Contributions	1,469	1,277	594
IBEW Local No. 82 Pension Plan [Member]
Multiemployer Plans [Line Items]
Multiemployer Plans, Surcharge	no
IBEW Local No. 82 Pension Plan [Member] | Multiemployer Plans, Pension [Member]
Multiemployer Plans [Line Items]
Entity Tax Identification Number	316127268
Multiemployer Plan Number	001
Multiemployer Plans, Certified Zone Status	red	red
Multiemployer Plans, Certified Zone Status, Date	Jun. 30, 2011	Jun. 30, 2010
Multiemployer Plans, Funding Improvement Plan and Rehabilitation Plan	implemented
Multiemployer Plan, Period Contributions	1,331	1,569	1,197
IBEW Local 648 Pension Plan [Member]
Multiemployer Plans [Line Items]
Multiemployer Plans, Surcharge	no
Multiemployer Plans, Collective-Bargaining Arrangement, Expiration Date	Aug. 31, 2012
IBEW Local 648 Pension Plan [Member] | Multiemployer Plans, Pension [Member]
Multiemployer Plans [Line Items]
Entity Tax Identification Number	316134845
Multiemployer Plan Number	001
Multiemployer Plans, Certified Zone Status	red	red
Multiemployer Plans, Certified Zone Status, Date	Feb. 28, 2011	Feb. 28, 2010
Multiemployer Plans, Funding Improvement Plan and Rehabilitation Plan	implemented
Multiemployer Plan, Period Contributions	722	781	641
Laborers Pension Trust Fund for Northern California [Member]
Multiemployer Plans [Line Items]
Multiemployer Plans, Surcharge	no
Multiemployer Plans, Collective-Bargaining Arrangement, Expiration Date	Jun. 30, 2012
Laborers Pension Trust Fund for Northern California [Member] | Multiemployer Plans, Pension [Member]
Multiemployer Plans [Line Items]
Entity Tax Identification Number	946277608
Multiemployer Plan Number	001
Multiemployer Plans, Certified Zone Status	yellow	yellow
Multiemployer Plans, Certified Zone Status, Date	May 31, 2011	May 31, 2010
Multiemployer Plans, Funding Improvement Plan and Rehabilitation Plan	implemented
Multiemployer Plan, Period Contributions	628	413	325
Local Union 212 IBEW Pension Trust Fund [Member]
Multiemployer Plans [Line Items]
Multiemployer Plans, Surcharge	no
Local Union 212 IBEW Pension Trust Fund [Member] | Multiemployer Plans, Pension [Member]
Multiemployer Plans [Line Items]
Entity Tax Identification Number	316127280
Multiemployer Plan Number	001
Multiemployer Plans, Certified Zone Status	yellow	yellow
Multiemployer Plans, Certified Zone Status, Date	Apr. 30, 2011	Apr. 30, 2010
Multiemployer Plans, Funding Improvement Plan and Rehabilitation Plan	implemented
Multiemployer Plan, Period Contributions	776	679	469
National Electrical Benefit Fund [Member]
Multiemployer Plans [Line Items]
Multiemployer Plans, Surcharge	no
Multiemployer Plans, Collective-Bargaining Arrangement, Expiration Date	May 31, 2014
National Electrical Benefit Fund [Member] | Multiemployer Plans, Pension [Member]
Multiemployer Plans [Line Items]
Entity Tax Identification Number	530181657
Multiemployer Plan Number	001
Multiemployer Plans, Certified Zone Status	green	green
Multiemployer Plans, Funding Improvement Plan and Rehabilitation Plan	no
Multiemployer Plan, Period Contributions	4,841	4,826	5,462
OE Pension Trust Fund [Member]
Multiemployer Plans [Line Items]
Multiemployer Plans, Surcharge	no
Multiemployer Plans, Collective-Bargaining Arrangement, Expiration Date	Mar. 31, 2016
OE Pension Trust Fund [Member] | Multiemployer Plans, Pension [Member]
Multiemployer Plans [Line Items]
Entity Tax Identification Number	946090764
Multiemployer Plan Number	001
Multiemployer Plans, Certified Zone Status	yellow	yellow
Multiemployer Plans, Funding Improvement Plan and Rehabilitation Plan	implemented
Multiemployer Plan, Period Contributions	1,367	1,035	1,061
Multiemployer Plan, Individually Insignificant Multiemployer Plans [Member] | Multiemployer Plans, Pension [Member]
Multiemployer Plans [Line Items]
Multiemployer Plan, Period Contributions	$ 15,324	$ 17,763	$ 21,103