Fair Value Measurements (Details) (Fair value on a recurring basis, USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Fair Value Assets and Liabilities Measured on Recurring Basis
Transfers of financial assets or liabilities within the fair value hierarchy	$ 0
Fair Value
Fair value assets and liabilities measured on recurring basis:
Total fair value assets and liabilities measured on recurring basis	(9,156)
Fair Value | Currency swap contracts
Fair value assets and liabilities measured on recurring basis:
Derivative assets	2,490
Fair Value | Interest-rate swap contracts
Fair value assets and liabilities measured on recurring basis:
Derivative liabilities	(12,421)
Fair Value | Warrants
Fair value assets and liabilities measured on recurring basis:
Derivative assets	775
Level 2
Fair value assets and liabilities measured on recurring basis:
Total fair value assets and liabilities measured on recurring basis	(9,931)
Level 2 | Currency swap contracts
Fair value assets and liabilities measured on recurring basis:
Derivative assets	2,490
Level 2 | Interest-rate swap contracts
Fair value assets and liabilities measured on recurring basis:
Derivative liabilities	(12,421)
Level 3
Fair value assets and liabilities measured on recurring basis:
Total fair value assets and liabilities measured on recurring basis	775
Level 3 | Warrants
Fair value assets and liabilities measured on recurring basis:
Derivative assets	$ 775