Fair Value Measurements - recurring basis (Details) - USD ($) $ in Thousands	1 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Fair value assets and liabilities measured on recurring basis:
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	$ 2,000
Exercise of warrants classified as Level 3 within the fair value hierarchy in exchange for marketable equity securities classified as Level 1	2,000
Fair value on a recurring basis | Level 1
Fair value assets and liabilities measured on recurring basis:
Marketable equity securities	1,254
Fair value on a recurring basis | Level 2 | Interest-rate swap contracts
Fair value assets and liabilities measured on recurring basis:
Derivative liabilities	7,655
Fair value on a recurring basis | Level 2 | Currency Swap
Fair value assets and liabilities measured on recurring basis:
Derivative assets	1,118
Fair value on a recurring basis | Level 3 | Warrants
Fair value assets and liabilities measured on recurring basis:
Derivative assets	43
Fair Value
Fair value assets and liabilities measured on recurring basis:
Marketable equity securities		$ 43
Fair Value | Currency Swap
Fair value assets and liabilities measured on recurring basis:
Derivative assets	1,118	929
Fair Value | Level 1
Fair value assets and liabilities measured on recurring basis:
Marketable equity securities	1,254
Fair Value | Level 2 | Interest-rate swap contracts
Fair value assets and liabilities measured on recurring basis:
Derivative assets		178
Derivative liabilities	7,655	7,663
Fair Value | Level 3 | Warrants
Fair value assets and liabilities measured on recurring basis:
Derivative assets	43	$ 2,220
Fair Value | Fair value on a recurring basis
Fair value assets and liabilities measured on recurring basis:
Marketable equity securities	1,254
Fair Value | Fair value on a recurring basis | Interest-rate swap contracts
Fair value assets and liabilities measured on recurring basis:
Derivative liabilities	7,655
Fair Value | Fair value on a recurring basis | Currency Swap
Fair value assets and liabilities measured on recurring basis:
Derivative assets	1,118
Fair Value | Fair value on a recurring basis | Warrants
Fair value assets and liabilities measured on recurring basis:
Derivative assets	$ 43