Employee Savings and Investment Plan (Additional Information) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
IRS deferral limit	$ 17,500	$ 17,000
Employee compensation subject to employer matching percent	6.00%
Employer contributions	$ 2,100,000	$ 1,700,000	$ 1,700,000
100% match [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employee compensation subject to employer matching percent	3.50%
100% match [Member] | 1% of compensation [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer matching contribution percent	100.00%
Employee compensation subject to employer matching percent	1.00%
50% match [Member] | 5% of compensation [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer matching contribution percent	50.00%
Employee compensation subject to employer matching percent	5.00%