Retirement Plans - Employee Retirement Savings Plans (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
401(k) retirement savings plan
Defined Contribution Pension and Other Postretirement Plans Disclosure [Abstract]
Employee contribution of eligible compensation for matching, percent	1
Employer matching contribution, percent	5.00%
Cost recognized to match employee 401(k) contributions	$ 1.7	$ 2.3	$ 2.1
Variable compensation program
Defined Contribution Pension and Other Postretirement Plans Disclosure [Abstract]
Employer matching contribution, percent	3.00%
Employer contribution amount	$ 0	$ 0.7	$ 0