Derivative Instruments, Hedging Activities and Fair Value (Details 5) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Unit Adjustment Liability, Infrastructure Transaction
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	[1]	$ 93,762	$ 106,343
Payments	[1]	(16,740)	(16,740)
Change in fair value to the unit adjustment liability	[1]	6,492	7,417
Balance at end of period	[1]	83,514	$ 97,020
Fair value measurements recurring | Level 2
Assets
Foreign currency forward exchange contracts		7,409		$ 4,485
Cross-currency interest rate swaps		10,455		52,989
Liabilities
Foreign currency forward exchange contracts		770		4,618
Cross-currency interest rate swaps		$ 0		$ 2,599

[1] See Note 6, Equity Method Investments, for additional information related to the unit adjustment liability.