Stockholders' Equity (Details 1) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2011
Stock option activity in shares and weighted average price
Options outstanding, beginning of period, shares	1,585,594	1,361,779
Options outstanding, beginning of period, weighted average price	$ 33.13	$ 32.46
Options granted, shares	0
Options granted, weighted average price	$ 0.00
Options canceled, shares	(85,403)
Options canceled, weighted average price	$ 31.51
Options exercised, shares	(11,877)
Options exercised, weighted average price	$ 13.84
Options outstanding, end of period, shares	1,488,314	1,361,779
Options outstanding, end of period, weighted average price	$ 33.38	$ 32.46
Options exercisable, end of period, shares	1,201,971
Options exercisable, end of period, weighted average price	$ 32.93