Stock-Based Compensation (Valuation Assumptions) (Details) (Employee Stock Option, Common Stock, USD $)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Employee Stock Option | Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Average expected option life (in years)	5 years 7 months 6 days	[1]	6 years	[1]	6 years	[1]
Volatility	54.00%	[2]	55.80%	[2]	56.60%	[2]
Risk-free interest rate	1.70%	[3]	1.00%	[3]	2.00%	[3]
Dividend Yield	0.00%	[4]	0.00%	[4]	0.00%	[4]
Weighted-average grant-date fair value per stock option	$ 7.41		$ 6.90		$ 4.55

[1] Determined by the historical stock option exercise behavior of the Company's employees (maximum term is 10 years).

[2] Measured using weekly price observations for a period equal to stock options' expected term.

[3] Based upon the U.S. Treasury yields in effect (for a period equaling the stock options' expected term)

[4] The Company has never paid cash dividends on its common stock and does not expect to declare any cash dividends