Share-Based Compensation (Summary of Stock Options Activity) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Weighted Average Exercise Price
Beginning of period (in dollars per share)	$ 16.05	$ 13.18	$ 10.97
Granted (in dollars per share)	$ 28.02	$ 23.50	$ 17.50
Cancelled (in dollars per share)	$ 21.95	$ 18.18	$ 14.53
Exercised (in dollars per share)	$ 11.66	$ 10.37	$ 7.81
End of period (in dollars per share)	$ 19.45	$ 16.05	$ 13.18
Number of Shares
Beginning of period (in shares)	2,483	2,632	2,912
Granted (in shares)	535	564	601
Cancelled (in shares)	(122)	(88)	(134)
Exercised (in shares)	(534)	(625)	(747)
End of period (in shares)	2,362	2,483	2,632