Derivative Instruments, Hedging Activities and Fair Value (Details 5) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014		Dec. 31, 2013
Fair value measurements recurring | Level 2
Assets
Foreign currency forward exchange contracts	$ 2,341		$ 1,256
Cross-currency interest rate swaps	24,473		26,001
Liabilities
Foreign currency forward exchange contracts	1,496		3,284
Cross-currency interest rate swaps	19,939		13,410
Unit Adjustment Liability, Infrastructure Transaction [Member]
Fair value of financial instruments
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value	100,201		106,343
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	(11,160)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Accretion Expense	$ 5,019	[1]

[1] See Note 5, Equity Method Investments, for additional information related to the unit adjustment liability.