Fair Value Measurements and the Fair Value Option - Marketable Securities, Narrative (Details) - KWE [Member] $ / shares in Units, shares in Millions, $ in Millions	Sep. 30, 2015 USD ($) $ / shares shares
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Shares in KWE (in shares) | shares	24.0
Market value of investment	$ 413.5
Investment cost basis	$ 401.5
Share price | $ / shares	$ 17.22
Percentage of investments hedged	84.40%
Fair Value	$ 12.4