Fair Value Measurements (Table)

6 Months Ended

Jun. 30, 2012

Fair Value Disclosures [Abstract]

Fair value measurements

		Level within	June 30,				December 31,
		the Fair Value	2012				2011
		Hierarchy	Book Value			Fair Value	Book Value		Fair Value
(Dollars in thousands)
Cash and cash equivalents		1	$	437,624	$	437,624	$	424,155	$	424,155
Short-term investments (1)(2)
	Government-backed securities (3)	1		100,738		100,738		127,039		127,039
Long-term investments (1)(4)
	Government-backed securities (3)	1		55,468		55,468		30,057		30,140
Long-term debt (5)
	6.95% Senior Notes	1		342,000		366,624		342,000		364,162
	6.7% Senior Notes	2		534,338		540,928		534,111		534,860

• Designated as held-to-maturity investments and recorded at amortized cost in the Consolidated Balance Sheet.
• Maturities are less than twelve months from the respective balance sheet dates.
• Includes U.S. treasuries and corporate notes guaranteed under the Federal Deposit Insurance Corporation's Temporary Liquidity Guarantee Program.
• At June 30, 2012, maturities range between 12 and 21 months.
• Excludes capital lease obligations and current portion of Long-term debt.