Fair Value Measurements and Derivative Instruments (Narrative) (Details) - USD ($)	6 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Derivative [Line Items]
Investment securities at a loss position for more than 12 months, aggregate unrealized holding losses (less than)	$ 1,000,000	$ 1,000,000
Investment securities at a loss position for more than 12 months, estimated fair value	24,000,000	12,000,000
Investment securities at a loss position for less than 12 months, aggregate unrealized holding losses	2,000,000	4,000,000
Investment securities at a loss position for less than 12 months, estimated fair value	132,000,000	171,000,000
Amount of ineffectiveness	0
Foreign exchange contracts
Derivative [Line Items]
Derivative notional amount	9,000,000	$ 13,000,000
Term Loan | Notes due December 2020
Derivative [Line Items]
Loan amount	300,000,000
Cash Flow Hedge | Interest rate swaps
Derivative [Line Items]
Derivative notional amount	$ 300,000,000
Fixed interest rate	0.8826%