|
Accounts receivable (Details) (USD $)
In Thousands, unless otherwise specified |
Dec. 31, 2013
|
Dec. 31, 2012
|
|---|---|---|
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||
| Accounts receivable | $ 60,587 | $ 96,043 |
|
Billed [Member]
|
||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||
| Accounts receivable | 45,757 | 76,155 |
|
Unbilled [Member]
|
||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||
| Accounts receivable | $ 14,830 | $ 19,888 |