Stock Plans (Details 3) (Restricted stock, USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Restricted stock
Number of Awards
Non-vested at the beginning of the period (in shares)	866	511	187
Granted (in shares)	880	809	530
Vested (in shares)	(481)	(410)	(186)
Forfeited (in shares)	(145)	(44)	(20)
Non-vested at the end of the period (in shares)	1,120	866	511
Weighted-Average Grant Date Fair Value
Non-vested at the beginning of the period (in dollars per share)	$ 24.43	$ 27.72	$ 20.01
Granted (in dollars per share)	$ 30.76	$ 23.94	$ 27.48
Vested (in dollars per share)	$ 25.12	$ 27.09	$ 20.66
Forfeited (in dollars per share)	$ 25.63	$ 28.97	$ 28.50
Non-vested at the end of the period (in dollars per share)	$ 28.95	$ 24.43	$ 27.72