Long-Term Debt (Senior Notes Due 2016) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended	12 Months Ended						12 Months Ended
	Dec. 31, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 6 5/8% Senior Notes Due 2016	Dec. 31, 2011 6 5/8% Senior Notes Due 2016	Jan. 13, 2006 6 5/8% Senior Notes Due 2016	Dec. 31, 2012 Maximum [Member] Debt Covenant [Member] Senior Notes [Member]
Debt Instrument [Line Items]
Stated interest rate	6.50%	6.50%			6.625%	6.625%	6.625%
Maturity					2016
Minimum debt amount guaranteed by subsidiaries					$ 5,000
Maximum Unrestricted Quarterly Dividends Allowable Under Debt Covenants								$ 0.20
Dividends per common share	$ 0.1875	$ 4.2725	$ 0.2746	$ 0.2420