Stockholders' Equity Stockholders' Equity (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jun. 30, 2013	Jun. 05, 2012
Stockholders' Equity Attributable to Parent [Abstract]
Preferred stock authorized, shares	5,000,000	5,000,000
Employee stock purchase, shares	864,457	3,547,431	1,487,642
Employee stock purchases	$ 17,343,000	$ 74,213,000	$ 22,932,000
Issuance of restricted stock awards, shares	212,136	237,413	352,391
Stock repurchase program, authorized amount				$ 50,000,000	$ 50,000,000
Number of shares held in treasury	2,192,982			2,192,982