Stock-Based Compensation (Details 3) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Stock Options
Weighted-average assumptions used to estimate fair value
Expected term	6 years 3 months	6 years 3 months	6 years 9 months
Expected stock price volatility (as a percent)	44.24%	39.76%	36.03%
Risk-free interest rate (as a percent)	1.05%	2.43%	2.70%
Expected dividend yield (as a percent)	3.41%	2.42%	2.42%
Other disclosures
Weighted-average fair value of options granted (in dollars per share)	$ 2.74	$ 3.85	$ 3.70
Unrecognized compensation cost	$ 4.30
Recognition period	2 years 6 months 22 days
Stock Options | Minimum
Weighted-average assumptions used to estimate fair value
Estimated dividend payments (in dollars per share)	$ 0.34
Stock Options | Maximum
Weighted-average assumptions used to estimate fair value
Estimated dividend payments (in dollars per share)	$ 0.44
Stock Options | Weighted-Average
Weighted-average assumptions used to estimate fair value
Estimated dividend payments (in dollars per share)	$ 0.39
Non-vested Shares
Other disclosures
Unrecognized compensation cost	$ 3.00
Recognition period	1 year 8 months 16 days
Percentage of all non-vested shares, granted prior to 2011, vesting on the third anniversary	100.00%
Number of equal increments over the first three anniversaries from the date of grant in which a majority of non-vested shares, granted after 2010, vest	3	3
Percentage of remaining non-vested shares, granted after 2010, that vest on the third anniversary	100.00%	100.00%
Number of Shares
Outstanding at the beginning of the period (in shares)	419,340	181,286	153,740
Granted (in shares)	332,113	300,224	85,747
Vested/Issued (in shares)	(143,626)	(53,671)	(48,201)
Forfeited (in shares)	(107,374)	(8,499)	(10,000)
Outstanding at the end of the period (in shares)	500,453	419,340	181,286
Weighted-Average Grant-Date Fair Value
Outstanding at the beginning of the period (in dollars per share)	$ 11.42	$ 11.05	$ 15.76
Granted (in dollars per share)	$ 9.91	$ 12.31	$ 11.93
Vested/Issued (in dollars per share)	$ 9.82	$ 15.04	$ 24.79
Forfeited (in dollars per share)	$ 11.09	$ 11.95	$ 24.86
Outstanding at the end of the period (in dollars per share)	$ 10.95	$ 11.42	$ 11.05
Performance Stock Units
Other disclosures
Period over which performance goals are measured	3 years
Percentage payout upon change of control	100.00%
Number of Shares
Outstanding at the beginning of the period (in shares)	169,600	24,250	57,450
Granted (in shares)	136,000	188,800	0
Vested/Issued (in shares)	0	(19,200)	0
Forfeited (in shares)	(65,900)	(24,250)	(33,200)
Outstanding at the end of the period (in shares)	239,700	169,600	24,250
Weighted-Average Grant-Date Fair Value
Outstanding at the beginning of the period (in dollars per share)	$ 11.34	$ 14.98	$ 20.52
Granted (in dollars per share)	$ 8.84	$ 11.34	$ 0.00
Vested/Issued (in dollars per share)	$ 0.00	$ 11.34	$ 0.00
Forfeited (in dollars per share)	$ 10.15	$ 14.98	$ 24.56
Outstanding at the end of the period (in dollars per share)	$ 10.25	$ 11.34	$ 14.98
Performance Stock Units | Minimum
Other disclosures
Percentage of award shares to be issued based on performance against goals	0.00%
Performance Stock Units | Maximum
Other disclosures
Percentage of award shares to be issued based on performance against goals	100.00%