Stockholders Equity (Share Repurchase Program) (Details) (USD $)	6 Months Ended	12 Months Ended	30 Months Ended
	Jun. 30, 2013	Dec. 31, 2011	Jun. 30, 2013
Equity [Abstract]
Stock repurchase program, authorized amount		$ 50,000,000
Stock repurchase program, shares acquired during period	394,397		469,471
Stock repurchase program, shares acquired during period, cost			$ 26,800,000
Stock repurchase program, shares acquired during period, weighted-average cost per share	$ 54.79