Employee and Non-Employee Director Stock and Benefit Plans - Stock Options/2007 Plan (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stock options
Number of Shares
Outstanding at the beginning of the period (in shares)	306,853	343,326	510,975
Granted (in shares)	0	0	0
Exercised (in shares)	(71,455)	(14,228)
Forfeited (in shares)	(192,733)	(22,245)	(167,649)
Outstanding at the end of the period (in shares)	42,665	306,853	343,326
Amount exercisable at the end of the period (in shares)	42,665	306,853	262,017
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 17.23	$ 17.29	$ 26.77
Exercised (in dollars per share)	16.26	14.28
Forfeited (in dollars per share)	18.71	20.09	46.18
Outstanding at the end of the period (in dollars per share)	12.17	17.23	17.29
Amount exercisable at the end of the period (in dollars per share)	$ 12.17	$ 17.23	$ 17.28
2007 Plan
Employee and non-employee director stock and benefit plans
Shares of common stock authorized	13,068,208
2007 Plan | Time-based option awards
Employee and non-employee director stock and benefit plans
Full vesting after the period, on anniversary of the grant	3 years
Directors' Equity Subplan | Restricted stock unit awards.
Employee and non-employee director stock and benefit plans
Value of shares granted at or shortly after the time of appointment	$ 100,000
Value of shares granted on the forty fifth day following each of the annual meetings of stockholders	$ 72,000
Vesting period, from first anniversary of grant date	3 years