Commitments and Contingencies (Details 4) (USD $)	12 Months Ended
	Dec. 31, 2011 Y Claimant
Employment Litigation - Whitaker lawsuit
Loss contingencies
Current employees filing lawsuit	1
Former employees filing lawsuit	1
Threshold age for members of class action (in years)	46
Punitive damages, statutory limit per claimant	$ 8,500
EEOC age-discrimination charges
Loss contingencies
Current employees filing lawsuit	1
Former employees filing lawsuit	6
Number of claimants not involved in Garcia lawsuit	1