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

6 Months Ended

Jun. 30, 2011

Long-term Debt Current And Noncurrent Abstract

Fair Value Of Long Term Debt Table [Text Block]

	June 30,					December 31,
Thousands		2011		2010		2010
Carrying amount	$	591,700	$	636,700	$	601,700
Estimated fair value	$	678,281	$	728,172	$	690,126