Share-based Compensation (Details 3) (SARs activity [Member], USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
SARs activity [Member]
Summary of SARs activity under the 2005 Plan
Stock Appreciation Rights (SARs), Outstanding, Beginning Balance (in shares)	207,234	597,392	805,910
Stock Appreciation Rights (SARs), Granted (in shares)	119,342	0	204,500
Stock Appreciation Rights (SARs), Cancelled/Forfeited (in shares)	(50,550)	(41,114)	(22,360)
Stock Appreciation Rights (SARs), Exercised (in shares)	(136,915)	(349,044)	(390,658)
Stock Appreciation Rights (SARs), Outstanding, Ending Balance (in shares)	139,111	207,234	597,392
SARs Weighted Average Exercise Price
Weighted Average Exercise Price, Outstanding, Beginning of the year (in dollars per share)	$ 25.85	$ 21.54	$ 16.35
Weighted Average Exercise Price, Granted (in dollars per share)	$ 49.31		$ 29.31
Weighted Average Exercise Price, Outstanding, End of the year (in dollars per share)	$ 41.02	$ 25.85	$ 21.54
Stock Appreciation Rights (SARs), Exercisable (in shares)	15,098
Weighted Average Exercise Price, Exercisable (in dollars per share)	$ 20.14
Weighted Average Remaining Contractual Life, Outstanding	63 months
Weighted Average Remaining Contractual Life, Exercisable	34 months
Weighted Average Grant Fair Value of SARs, Outstanding (in dollars per share)	$ 19.13
Weighted Average Fair Value of SARs, Exercisable (in dollars per share)	$ 30.01
Aggregate Intrinsic Value, Outstanding	$ 1,575
Aggregate Intrinsic Value. Exercisable	$ 473