Stock-Based Compensation (Details 3) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Other Disclosures
Total unrecognized compensation cost related to the unvested awards	$ 20.8
Total weighted average remaining term of unvested awards	2 years 6 months
Compensation cost recognized in selling, general and administrative expenses	9.6	5.8	5.3
Second Amended and Restated 2004 Stock Incentive Plan | Restricted stock and deferred shares
Summary of unvested restricted stock and deferred shares activity and related information
Unvested at beginning of year (in shares)	237	153	162
Granted (in shares)	142	170	115
Cancelled/Forfeitures (in shares)	(16)	(8)	(14)
Vested (in shares)	(103)	(78)	(110)
Unvested at end of year (in shares)	260	237	153
Weighted Average Grant Date Fair Value
Unvested at beginning of period (in dollars per share)	$ 35.45	$ 30.33	$ 31.39
Granted (in dollars per share)	$ 54.80	$ 37.62	$ 29.51
Cancelled/Forfeitures (in dollars per share)	$ 37.44	$ 30.66	$ 31.12
Vested (in dollars per share)	$ 35.25	$ 30.61	$ 30.94
Unvested at end of period (in dollars per share)	$ 45.58	$ 35.45	$ 30.33
Other Disclosures
Total fair value of shares vested	5.6	2.5	2.5
Total unrecognized compensation cost related to the unvested awards	9.4
Total weighted average remaining term of unvested awards	2 years 1 month 6 days
Compensation cost recognized in selling, general and administrative expenses	5.1	2.9	2.4
Estimated forfeiture rate (as a percent)	9.00%	9.00%	9.00%
Aggregate intrinsic value of restricted stock granted and outstanding	16.1
Second Amended and Restated 2004 Stock Incentive Plan | Restricted stock and deferred shares | Class A common stock
Other Disclosures
Company's closing Common Stock price (in dollars per share)	$ 61.87
Management Stock Purchase Plan | Restricted stock | Class A common stock
Other Disclosures
Company's closing Common Stock price (in dollars per share)	$ 61.87
Management Stock Purchase Plan | Restricted stock units (RSUs)
Summary of unvested restricted stock and deferred shares activity and related information
Granted (in shares)	45	64	99
Cancelled/Forfeitures (in shares)	(14)	(110)	(10)
Weighted Average Grant Date Fair Value
Granted (in dollars per share)	$ 18.05	$ 15.68	$ 16.25
Other Disclosures
Total unrecognized compensation cost related to the unvested awards	0.8
Total weighted average remaining term of unvested awards	1 year 4 months 24 days
Compensation cost recognized in selling, general and administrative expenses	0.7	0.8	1.3
Estimated forfeiture rate (as a percent)	6.30%	6.30%	6.30%
Dividend declared and unpaid	$ 0.1