Equity Award Plans Equity Award Plans (Details 3) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Performance shares
Shares
Outstanding at the beginning of the period (in shares)	53,874
Granted (in shares)	168,029
Vested (in shares)	0
Forfeited or canceled (in shares)	(18,063)
Outstanding at the end of the period (in shares)	203,840
Weighted Average Grant Date Fair Value
Outstanding at the beginning of the period (in dollars per share)	$ 52.38
Granted (in dollars per share)	$ 12.13
Vested (in dollars per share)	$ 0.00
Forfeited (in dollars per share)	$ 20.55
Outstanding at the end of the period (in dollars per share)	$ 22.02
Weighted average period over which unrecognized compensation costs will be recognized	1 year 8 months 12 days
Unrecognized compensation costs related to performance-based share units compensation arrangements granted	$ 1.1
Performance shares | Minimum
Equity Award Plans
Vesting period	2 years
Percentage of total shareholders return depending on achievement of the goals	0.00%
Performance shares | Maximum
Equity Award Plans
Vesting period	3 years
Percentage of total shareholders return depending on achievement of the goals	200.00%
Restricted stock units
Equity Award Plans
Vesting period	3 years
Shares
Outstanding at the beginning of the period (in shares)	209,511
Granted (in shares)	597,434
Vested (in shares)	115,115
Forfeited or canceled (in shares)	(68,145)
Outstanding at the end of the period (in shares)	623,685	209,511
Weighted Average Grant Date Fair Value
Outstanding at the beginning of the period (in dollars per share)	$ 63.67
Granted (in dollars per share)	$ 9.82	$ 34.03	$ 63.17
Vested (in dollars per share)	$ 83.33
Forfeited (in dollars per share)	$ 15.47
Outstanding at the end of the period (in dollars per share)	$ 13.73	$ 63.67
Stock options
Equity Award Plans
Vesting period	3 years
Weighted Average Grant Date Fair Value
Weighted average period over which unrecognized compensation costs will be recognized	1 year 10 months 24 days
Unrecognized compensation costs related to stock options granted	1.4
Employee stock
Weighted Average Grant Date Fair Value
Employer contribution, as a percentage of participant's actual payroll deduction	15.00%
Employer contribution after five years of continuous participation , as a percentage of participant's actual payroll deduction	20.00%
Period of continuous employee participation required to receive employer contribution of 20% of participant's actual payroll deduction	5 years
Number of shares authorized	3,500,000
Number of shares purchased under the plan	794,680	217,900	86,200
Stock-based compensation expense	0.4	0.3	0.5
2002 Plan
Weighted Average Grant Date Fair Value
Weighted average period over which unrecognized compensation costs will be recognized	2 years
Number of shares authorized	4,300,000
Stock-based compensation expense	8.0	10.1	7.3
2002 Plan | Restricted stock units
Weighted Average Grant Date Fair Value
Unrecognized compensation costs	$ 2.2