Derivative Instruments, Hedging Activities and Fair Value (Details 5) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2015	Jun. 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]	(11,160)	(11,160)
Change in fair value to the unit adjustment liability	[1]	4,409	5,019
Balance at end of period	[1],[2]	87,012	$ 100,201
Fair value measurements recurring | Level 2
Assets
Foreign currency forward exchange contracts		2,455		$ 4,485
Cross-currency interest rate swaps		70,435		52,989
Liabilities
Foreign currency forward exchange contracts		4,504		4,618
Cross-currency interest rate swaps		$ 1,002		$ 2,599

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

[2] Does not total due to rounding.