Related person transactions (Details) (Chief Executive Officer, USD $)	12 Months Ended
Dec. 31, 2013
Chief Executive Officer
Related person transactions.
Related Party Transaction, Purchases from Related Party	$ 221,000

Purchases during the period (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

No definition available.

Name:	us-gaap_RelatedPartyTransactionPurchasesFromRelatedParty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration