Share-Based Compensation (Narrative) (Details) (USD $)	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 Restricted Stock [Member]	Sep. 30, 2013 Restricted Stock [Member]	Sep. 30, 2014 Employee Stock Purchase Plan (ESPP) [Member]	Apr. 12, 2011 Employee Stock Purchase Plan (ESPP) [Member] offering
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	4,902,000
Shares available for future grant	2,306,000				2,476,000
Maximum term of grants	10 years
Options vested and exercisable, period	5 years
Weighted average grant-date fair value of stock options granted (in dollars per share)	$ 8.24	$ 6.81
Restricted stock granted			14,000	6,000
Weighted average grant date fair value of restricted stock granted			$ 28.02	$ 23.50
Requisite service period for plan participation eligibility					2 years
Number of additional offerings						5
Stock options authorized to issue to employees					4,050,000