Fair Value Measurements - recurring basis (Details) (Fair value on a recurring basis, USD $) In Thousands, unless otherwise specified	Mar. 31, 2015
Fair Value
Fair value assets and liabilities measured on recurring basis:
Marketable equity securities	$ 38
Total fair value, net asset (liability)	(1,175)
Fair Value | Interest-rate swap contracts
Fair value assets and liabilities measured on recurring basis:
Derivative liabilities	(7,820)
Fair Value | Currency Swap
Fair value assets and liabilities measured on recurring basis:
Derivative assets	3,603
Fair Value | Warrants
Fair value assets and liabilities measured on recurring basis:
Derivative assets	3,004
Level 1
Fair value assets and liabilities measured on recurring basis:
Marketable equity securities	38
Total fair value, net asset (liability)	38
Level 2
Fair value assets and liabilities measured on recurring basis:
Total fair value, net asset (liability)	(4,217)
Level 2 | Interest-rate swap contracts
Fair value assets and liabilities measured on recurring basis:
Derivative liabilities	(7,820)
Level 2 | Currency Swap
Fair value assets and liabilities measured on recurring basis:
Derivative assets	3,603
Level 3
Fair value assets and liabilities measured on recurring basis:
Total fair value, net asset (liability)	3,004
Level 3 | Warrants
Fair value assets and liabilities measured on recurring basis:
Derivative assets	$ 3,004