Stock-Based Compensation (Narrative) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options exercised			16,100
Stock-based compensation expense	$ 3,699	$ 2,579	$ 6,917	$ 5,744
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock incentive plan, vesting period			4 years
Weighted Average Grant Date Fair Value, Granted			$ 31.75
Unrecognized compensation expense	12,400		12,400
Weighted-average period for recognition of compensation cost			2 years 3 months 11 days
Number of shares granted			398,697
Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	2,100		2,100
Weighted-average period for recognition of compensation cost			2 years 1 month 6 days
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 0		$ 0
Vesting Two Years From January 31 of Grant Year [Member] | Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock incentive plan, vesting period			24 months
Vesting percentage			50.00%
Vesting Three Years From January 31 of Grant Year [Member] | Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock incentive plan, vesting period			36 months
Vesting percentage			25.00%
Vesting Four Years From January 31 of Grant Year [Member] | Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock incentive plan, vesting period			48 months
Vesting percentage			25.00%