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

6 Months Ended

Jun. 30, 2012

Long-term Debt Current And Noncurrent Abstract

Fair Value Of Long Term Debt Table [Text Block]

	June 30,					December 31,
Thousands		2012		2011		2011
Carrying amount	$	641,700	$	591,700	$	681,700
Estimated fair value	$	768,429	$	678,281	$	808,724