Stockholders' Equity Repurchases of Common Stock (Details) (USD $)	0 Months Ended	1 Months Ended	12 Months Ended
	Nov. 30, 2012	Dec. 31, 2012	Dec. 31, 2012
Stockholders' Equity Note [Abstract]
Treasury stock, shares acquired	256,262	873,146	1,129,408
Treasury stock acquired, average price paid per share	$ 21.58	$ 24.26	$ 23.65
Stock repurchase program, remaining authorized repurchase amount	$ 94,470,000	$ 73,268,000