Retirement Plans (401(k) Savings Plan) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Compensation and Retirement Disclosure [Abstract]
Employer discretionary contribution percent	4.00%
Maximum annual contribution per employee percent	50.00%
Employer matching contribution percent	4.00%
Employer matching contribution amount	$ 1.11	$ 0.92	$ 0.86
Contribution to 401(k) savings plan	2.3	2.0	1.8
Employer total contribution amount	$ 3.4	$ 2.9	$ 2.6