Commitments and Contingencies, purchase commitments (Details) (BOSS Installation, USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012
BOSS Installation
Long-term Purchase Commitment [Line Items]
Purchase commitment required payments	$ 162.2
Purchase commitment required payments made	$ 83.9

The minimum amount the entity agreed to spend under the long-term purchase commitment.

No definition available.

Name:	us-gaap_LongTermPurchaseCommitmentAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration