Borrowings (Details 2) (USD $)	Jun. 30, 2011
3.5% Senior Convertible Debentures due 2034 [Member]
Conversion prices and numbers of shares used to determine aggregate consideration upon conversion of convertible debt
Conversion Price	$ 20.74
Number of Shares	407,224
4.0% Senior Subordinated Convertible Debentures due 2034 [Member]
Conversion prices and numbers of shares used to determine aggregate consideration upon conversion of convertible debt
Conversion Price	$ 20.74
Number of Shares	13,118,193
7.25% Senior Subordinated Convertible Debentures due 2037 [Member]
Conversion prices and numbers of shares used to determine aggregate consideration upon conversion of convertible debt
Conversion Price	$ 27.09
Number of Shares	9,226,975