Stock Repurchase Plan (Narrative) (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended	12 Months Ended
Nov. 03, 2003	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Stock Repurchase Plan [Abstract]
Authorized repurchase value of common stock	$ 15
Remaining authorized share repurchases		$ 80.0	$ 107.7	$ 90.0

The remaining repurchase amount authorized by an entity's Board of Directors under a stock repurchase plan.

No definition available.

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