Subsequent Events (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Feb. 10, 2012	Dec. 31, 2011	Sep. 30, 2001
Subsequent Event
Long-term Purchase Commitment, Amount	$ 21.0
Share repurchase authorization increase		2.8
Stock Repurchase Shares Authorized		5.0	2.2	15.4

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