Pension Plan and Employee Benefits, Fair Value of Pension Plan Assets (Details) (Pension Benefits [Member], USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 341,892	$ 310,197
Interest Accrual	2,149	2,198
Total net assets	344,041	312,395	242,513
Cash and cash equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6,336	7,775
Common Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	16,319	15,242
Preferred Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	379	291
Obligations of U.S. Government and U.S. Government Agencies [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	32,734	28,501
Mutual funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	25,042	9,144
Private Equity Funds, Domestic [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	54,198	63,864
Private Equity Funds, Foreign [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	39,943	30,813
Real estate funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	17,341	16,349
Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,587	2,892
Corporate debt [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	147,013	135,326
Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	41,740	9,144
Level 1 [Member] | Cash and cash equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 1 [Member] | Common Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	16,319	0
Level 1 [Member] | Preferred Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	379	0
Level 1 [Member] | Obligations of U.S. Government and U.S. Government Agencies [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 1 [Member] | Mutual funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	25,042	9,144
Level 1 [Member] | Private Equity Funds, Domestic [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 1 [Member] | Private Equity Funds, Foreign [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 1 [Member] | Real estate funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 1 [Member] | Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 1 [Member] | Corporate debt [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	280,224	281,812
Level 2 [Member] | Cash and cash equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6,336	7,775
Level 2 [Member] | Common Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	15,242
Level 2 [Member] | Preferred Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	291
Level 2 [Member] | Obligations of U.S. Government and U.S. Government Agencies [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	32,734	28,501
Level 2 [Member] | Mutual funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 2 [Member] | Private Equity Funds, Domestic [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	54,198	63,864
Level 2 [Member] | Private Equity Funds, Foreign [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	39,943	30,813
Level 2 [Member] | Real estate funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 2 [Member] | Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 2 [Member] | Corporate debt [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	147,013	135,326
Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	19,928	19,241	17,839
Level 3 [Member] | Cash and cash equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 3 [Member] | Common Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 3 [Member] | Preferred Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 3 [Member] | Obligations of U.S. Government and U.S. Government Agencies [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 3 [Member] | Mutual funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 3 [Member] | Private Equity Funds, Domestic [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 3 [Member] | Private Equity Funds, Foreign [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 3 [Member] | Real estate funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	17,341	16,349	14,568
Level 3 [Member] | Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,587	2,892	3,271
Level 3 [Member] | Corporate debt [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0