Fair Value Measurement (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ 8,703	$ 2,109	$ 19,555	$ 1,981
Other Contract [Member] | Other Expense [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net			$ 17,155
Level III [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Inputs, Discount for Lack of Marketability			32.00%