Financing Arrangement (Narrative) (Details) (USD $)				1 Months Ended		1 Months Ended			1 Months Ended	42 Months Ended		1 Months Ended	3 Months Ended	36 Months Ended
	Jun. 30, 2013	Mar. 31, 2013		Jul. 31, 2011 Convertible Note Hedge	Jul. 14, 2011 Convertible Note Hedge	Jul. 31, 2011 Warrants	Jun. 30, 2013 Warrants	Jul. 14, 2011 Warrants	Aug. 31, 2011 Revolving Credit Facility [Member]	Feb. 29, 2016 Revolving Credit Facility [Member]	Aug. 30, 2012 Revolving Credit Facility [Member]	Jul. 31, 2011 0.75% Convertible Senior Notes Due 2016 days	Jun. 30, 2013 0.75% Convertible Senior Notes Due 2016	Jun. 30, 2016 0.75% Convertible Senior Notes Due 2016	Jul. 14, 2011 0.75% Convertible Senior Notes Due 2016	Jul. 14, 2011 0.75% Convertible Senior Notes Due 2016 Liability Component	Jul. 14, 2011 0.75% Convertible Senior Notes Due 2016 Equity Component
Financing Arrangements
Principal amount	$ 632,500,000	$ 632,500,000
Contractual interest rate of 0.75% Convertible Senior Notes due 2016	0.75%	0.75%											0.75%		0.75%
Convertible Senior Notes due description												2016	2016
0.75% Convertible Senior Notes due 2016 maturity date									Feb. 29, 2016			Jul. 15, 2016
Conversion rate of Notes												31.5075
Face amount of Notes															1,000
Initial conversion price per share of Notes													$ 31.74		$ 31.74
Number of trading days greater than or equal to the initial conversion price												20
Consecutive trading days under conversion trigger												30
Trigger price as percent of conversion price												130.00%
Trigger price												$ 41.26
Number of trading day that trading price falls below 98% of last reported sales price multiplied by conversion rate												5
Consecutive trading days under conversion trigger, trading price												10
Debt trading price as a percentage of stock price times conversion rate												98.00%
Convertible Senior Notes, Carrying Value	564,000,000	559,000,000	[1]													525,000,000
Effective interest rate															4.54%
Debt issuance costs											2,000,000				15,000,000	13,000,000	2,000,000
Debt instrument remaining discount amortization period														3 years 0 months
Shares covered by Hedge Transactions					19,900,000
Strike price for convertible note hedge					$ 31.74
Amount paid for Convertible Note Hedge				107,000,000
Shares covered by warrants issuance								19,900,000
Strike price of warrants							41.14	41.14
Proceeds from Warrants transaction						65,000,000
Line of Credit Facility
Line of Credit Facility, Maximum Borrowing Capacity											500,000,000
Line of Credit Facility Term										3 years 6 months
Option To Request Additional Commitments On Credit Facility											$ 250,000,000

[1] Derived from audited consolidated financial statements.