Retirement and Employee Benefit Plans (Fair Value Measurement of Pension Plan Assets) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Large Cap Growth Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 4,588	[1]	$ 3,792	[1]
Large Cap Growth Equity [Member] | Quoted Prices in Active Markets for Identical Assets, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,588	[1]	3,792	[1]
Large Cap Value Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,257	[2]	3,689	[2]
Large Cap Value Equity [Member] | Quoted Prices in Active Markets for Identical Assets, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,257	[2]	3,689	[2]
Large Cap Core Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11,564	[3]	10,849	[3]
Large Cap Core Equity [Member] | Significant Observable Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11,564	[3]	10,849	[3]
Small Cap Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,792	[4]	2,201	[4]
Small Cap Equity [Member] | Quoted Prices in Active Markets for Identical Assets, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,792	[4]	2,201	[4]
International Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21,891	[5]	16,719	[5]
International Equity [Member] | Quoted Prices in Active Markets for Identical Assets, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21,891	[5]	16,719	[5]
Emerging Market Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,454	[6]	3,377	[6]
Emerging Market Equity [Member] | Significant Observable Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,454	[6]	3,377	[6]
Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	31,021	[7]	25,192	[7]
Fixed Income [Member] | Significant Observable Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	31,021	[7]	25,192	[7]
Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,780		2,204
Cash and Cash Equivalents [Member] | Quoted Prices in Active Markets for Identical Assets, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,780		2,204
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	83,347		68,023
Equity Securities [Member] | Quoted Prices in Active Markets for Identical Assets, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	36,308		28,605
Equity Securities [Member] | Significant Observable Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 47,039		$ 39,418

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

[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.

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

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

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

[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.