Retirement and Employee Benefit Plans (Fair Value Measurement of Pension Plan Assets) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010
Equity Securities [Member]
Fair value of plan assets	$ 68,023		$ 56,949
Emerging Markets Equity [Member]
Fair value of plan assets	3,377	[1]
Large Cap Growth Equity [Member]
Fair value of plan assets	3,792	[2]	5,937	[2]
Large Cap Value Equity [Member]
Fair value of plan assets	3,689	[3]	5,838	[3]
Large Cap Core Equity [Member]
Fair value of plan assets	10,849	[4]	8,062	[4]
Small Cap Equity [Member]
Fair value of plan assets	2,201	[5]	6,662	[5]
International Equity [Member]
Fair value of plan assets	16,719	[6]	8,333	[6]
Fixed Income [Member]
Fair value of plan assets	25,192	[7]	18,539	[1]
Cash and Cash Equivalents [Member]
Fair value of plan assets	2,204		3,578
Quoted Prices in Active Markets for Identical Assets, Level 1 [Member] | Equity Securities [Member]
Fair value of plan assets	28,605		56,949
Quoted Prices in Active Markets for Identical Assets, Level 1 [Member] | Emerging Markets Equity [Member]
Fair value of plan assets	0	[1]
Quoted Prices in Active Markets for Identical Assets, Level 1 [Member] | Large Cap Growth Equity [Member]
Fair value of plan assets	3,792	[2]	5,937	[2]
Quoted Prices in Active Markets for Identical Assets, Level 1 [Member] | Large Cap Value Equity [Member]
Fair value of plan assets	3,689	[3]	5,838	[3]
Quoted Prices in Active Markets for Identical Assets, Level 1 [Member] | Large Cap Core Equity [Member]
Fair value of plan assets	0	[4]	8,062	[4]
Quoted Prices in Active Markets for Identical Assets, Level 1 [Member] | Small Cap Equity [Member]
Fair value of plan assets	2,201	[5]	6,662	[5]
Quoted Prices in Active Markets for Identical Assets, Level 1 [Member] | International Equity [Member]
Fair value of plan assets	16,719	[6]	8,333	[6]
Quoted Prices in Active Markets for Identical Assets, Level 1 [Member] | Fixed Income [Member]
Fair value of plan assets	0	[7]	18,539	[1]
Quoted Prices in Active Markets for Identical Assets, Level 1 [Member] | Cash and Cash Equivalents [Member]
Fair value of plan assets	2,204		3,578
Significant Observable Inputs, Level 2 [Member] | Equity Securities [Member]
Fair value of plan assets	39,418		0
Significant Observable Inputs, Level 2 [Member] | Emerging Markets Equity [Member]
Fair value of plan assets	3,377	[1]
Significant Observable Inputs, Level 2 [Member] | Large Cap Growth Equity [Member]
Fair value of plan assets	0	[2]	0	[2]
Significant Observable Inputs, Level 2 [Member] | Large Cap Value Equity [Member]
Fair value of plan assets	0	[3]	0	[3]
Significant Observable Inputs, Level 2 [Member] | Large Cap Core Equity [Member]
Fair value of plan assets	10,849	[4]	0	[4]
Significant Observable Inputs, Level 2 [Member] | Small Cap Equity [Member]
Fair value of plan assets	0	[5]	0	[5]
Significant Observable Inputs, Level 2 [Member] | International Equity [Member]
Fair value of plan assets	0	[6]	0	[6]
Significant Observable Inputs, Level 2 [Member] | Fixed Income [Member]
Fair value of plan assets	25,192	[7]	0	[1]
Significant Observable Inputs, Level 2 [Member] | Cash and Cash Equivalents [Member]
Fair value of plan assets	0		0
Significant Unobservable Inputs, Level 3 [Member] | Equity Securities [Member]
Fair value of plan assets	0		0
Significant Unobservable Inputs, Level 3 [Member] | Emerging Markets Equity [Member]
Fair value of plan assets	0	[1]
Significant Unobservable Inputs, Level 3 [Member] | Large Cap Growth Equity [Member]
Fair value of plan assets	0	[2]	0	[2]
Significant Unobservable Inputs, Level 3 [Member] | Large Cap Value Equity [Member]
Fair value of plan assets	0	[3]	0	[3]
Significant Unobservable Inputs, Level 3 [Member] | Large Cap Core Equity [Member]
Fair value of plan assets	0	[4]	0	[4]
Significant Unobservable Inputs, Level 3 [Member] | Small Cap Equity [Member]
Fair value of plan assets	0	[5]	0	[5]
Significant Unobservable Inputs, Level 3 [Member] | International Equity [Member]
Fair value of plan assets	0	[6]	0	[6]
Significant Unobservable Inputs, Level 3 [Member] | Fixed Income [Member]
Fair value of plan assets	0	[7]	0	[1]
Significant Unobservable Inputs, Level 3 [Member] | Cash and Cash Equivalents [Member]
Fair value of plan assets	$ 0		$ 0

[1] (6) An institutional fund that invests primarily in the equity securities of companies domiciled in emerging markets. (7) An institutional fund that seeks to replicate the performance of the Barclays Capital Long-Term Corporate Bond Index before fees through a sampling process.

[2] (1) Mutual fund that seeks to invest in a diversified portfolio of stocks with price appreciation growth opportunities.

[3] (2) Mutual fund that seeks to invest in a diversified portfolio of stocks that will increase in value over the long-term as well as provide current income.

[4] (3) An institutional fund that seeks to replicate the performance of the S&P 500 Index before fees.

[5] (4) Mutual fund that seeks to invest in a diversified portfolio of stocks with small market capitalizations.

[6] (5) Mutual funds that invest primarily in equity securities of companies domiciled outside of the United States, primarily in developed markets.

[7] (7) An institutional fund that seeks to replicate the performance of the Barclays Capital Long-Term Corporate Bond Index before fees through a sampling process.