Condensed Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Condensed Consolidated Statements of Comprehensive Income [Abstract]
Net income	$ 1,409	$ 55,874
Other comprehensive income, net of income taxes:
Pension, postretirement and other post-employment benefits, reclassifications into net income	463	573
Unrealized gains (losses) on available-for-sale securities	252	747
Unrealized gains and losses on derivatives, net of reclassifications into net income:
Unrealized gains (losses) on derivatives	1,760	9,501
Reclassifications of (gains) losses into net income	4,825	(2,124)
Total other comprehensive income	7,300	8,697
Total comprehensive income	$ 8,709	$ 64,571