Fair Value Measurements - recurring basis (Details) - Fair value on a recurring basis $ in Thousands	Jun. 30, 2015 USD ($)
Fair Value
Fair value assets and liabilities measured on recurring basis:
Marketable equity securities	$ 46
Fair Value | Interest-rate swap contracts
Fair value assets and liabilities measured on recurring basis:
Derivative assets	1,524
Derivative liabilities	7,015
Fair Value | Currency Swap
Fair value assets and liabilities measured on recurring basis:
Derivative assets	303
Derivative liabilities	1,570
Fair Value | Warrants
Fair value assets and liabilities measured on recurring basis:
Derivative assets	2,190
Level 1
Fair value assets and liabilities measured on recurring basis:
Marketable equity securities	46
Level 2 | Interest-rate swap contracts
Fair value assets and liabilities measured on recurring basis:
Derivative assets	1,524
Derivative liabilities	7,015
Level 2 | Currency Swap
Fair value assets and liabilities measured on recurring basis:
Derivative assets	303
Derivative liabilities	1,570
Level 3 | Warrants
Fair value assets and liabilities measured on recurring basis:
Derivative assets	$ 2,190