Employee Stock Benefit Plans (Nonvested Stock Option Activity) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares [Roll Forward]
Nonvested at beginning of period	347,591	422,757	550,120
Granted	203,825	163,042	168,939
Vested	(201,865)	(202,115)	(283,185)
Forfeited	(7,275)	(36,093)	(13,117)
Nonvested at end of period	342,276	347,591	422,757
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Nonvested at beginning of period, weighted-average value (in USD per share)	$ 9.11	$ 7.53	$ 4.81
Granted, weighted-average value (in USD per share)	$ 8.42	$ 9.33	$ 12.58
Vested, weighted-average value (in USD per share)	$ 8.47	$ 5.76	$ 6.87
Forfeited, weighted-average value (in USD per share)	$ 9.78	$ 10.40	$ 7.02
Nonvested at end of period, weighted-average value (in USD per share)	$ 9.07	$ 9.11	$ 7.53