Fair Value Measurements (Details) (Fair value on a recurring basis, USD $) In Thousands, unless otherwise specified	Dec. 31, 2014
Fair Value
Fair value assets and liabilities measured on recurring basis:
Total fair value assets and liabilities measured on recurring basis	$ (4,293)
Fair Value | Interest-rate swap contracts
Fair value assets and liabilities measured on recurring basis:
Derivative assets	178
Derivative liabilities	(7,663)
Fair Value | Currency Swap
Fair value assets and liabilities measured on recurring basis:
Marketable equity securities	43
Derivative assets	929
Fair Value | Warrants
Fair value assets and liabilities measured on recurring basis:
Derivative assets	2,220
Level 1
Fair value assets and liabilities measured on recurring basis:
Total fair value assets and liabilities measured on recurring basis	43
Level 1 | Currency Swap
Fair value assets and liabilities measured on recurring basis:
Marketable equity securities	43
Level 2
Fair value assets and liabilities measured on recurring basis:
Total fair value assets and liabilities measured on recurring basis	(6,556)
Level 2 | Interest-rate swap contracts
Fair value assets and liabilities measured on recurring basis:
Derivative assets	178
Derivative liabilities	(7,663)
Level 2 | Currency Swap
Fair value assets and liabilities measured on recurring basis:
Derivative assets	929
Level 3
Fair value assets and liabilities measured on recurring basis:
Total fair value assets and liabilities measured on recurring basis	2,220
Level 3 | Warrants
Fair value assets and liabilities measured on recurring basis:
Derivative assets	$ 2,220