Cost and Fair Value Basis of Long-Term Debt (tables)

3 Months Ended

Mar. 31, 2012

Long-term Debt Current And Noncurrent Abstract

Fair Value Of Long Term Debt Table [Text Block]

	March 31,					December 31,
Thousands		2012		2011		2011
Carrying amount	$	641,700	$	601,700	$	681,700
Estimated fair value		742,852		680,436		808,724