Stock-Based Compensation (Details 2) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Vested and exercisable | Minimum
Exercise price per share
Exercise price per share (in dollars per share)	$ 21.03	$ 21.03
Vested and exercisable | Maximum
Exercise price per share
Exercise price per share (in dollars per share)	$ 29.05	$ 26.83
Unvested | Minimum
Exercise price per share
Exercise price per share (in dollars per share)	$ 22.86	$ 21.03
Unvested | Maximum
Exercise price per share
Exercise price per share (in dollars per share)	$ 34.43	$ 29.16
Outstanding | Minimum
Exercise price per share
Exercise price per share (in dollars per share)	$ 21.03	$ 21.03
Outstanding | Maximum
Exercise price per share
Exercise price per share (in dollars per share)	$ 34.43	$ 29.16
Granted | Maximum
Exercise price per share
Exercise price per share (in dollars per share)	$ 34.43
Exercised | Minimum
Exercise price per share
Exercise price per share (in dollars per share)	$ 21.03
Exercised | Maximum
Exercise price per share
Exercise price per share (in dollars per share)	$ 26.83
Vested year-to-date | Minimum
Exercise price per share
Exercise price per share (in dollars per share)	$ 21.03
Vested year-to-date | Maximum
Exercise price per share
Exercise price per share (in dollars per share)	$ 29.05
Options and SARs
Options and SARs
Vested and exercisable at the beginning of the period (in shares)	524
Unvested at the beginning of the period (in shares)	194
Total outstanding at the beginning of the period (in shares)	718
Granted (in shares)	49
Exercised (in shares)	(14)
Vested and exercisable at the end of the period (in shares)	577	524
Unvested at the end of the period (in shares)	176	194
Total outstanding at the end of the period (in shares)	753	718
Vested year-to-date (in shares)	66
Weighted average exercise price
Vested and exercisable at the beginning of the period (in dollars per share)	$ 23.84
Unvested at the beginning of the period (in dollars per share)	$ 24.83
Total outstanding at the beginning of the period (in dollars per share)	$ 24.11
Granted (in dollars per share)	$ 34.43
Exercised (in dollars per share)	$ 24.03
Vested and exercisable at the end of the period (in dollars per share)	$ 24.14	$ 23.84
Unvested at the end of the period (in dollars per share)	$ 27.92	$ 24.83
Total outstanding at the end of the period (in dollars per share)	$ 26.03	$ 24.11
Vested during year (in dollars per share)	$ 23.74
Aggregate intrinsic value
Vested and exercisable at the beginning of the period (in dollars)	$ 4,981
Unvested at the beginning of the period (in dollars)	1,650
Total outstanding at the beginning of the period (in dollars)	6,631
Exercised (in dollars)	130
Vested and exercisable at the end of the period (in dollars)	6,119	4,981
Unvested at the end of the period (in dollars)	1,151	1,650
Total outstanding at the end of the period (in dollars)	7,270	6,631
Vested during year (in dollars)	$ 710
Weighted average fair value
Vested and exercisable at the beginning of the period (in dollars per share)	$ 5.35
Unvested at the beginning of the period (in dollars per share)	$ 4.57
Total outstanding at the beginning of the period (in dollars per share)	$ 5.14
Granted (in dollars per share)	$ 5.95
Exercised (in dollars per share)	$ 5.70
Vested and exercisable at the end of the period (in dollars per share)	$ 5.26	$ 5.35
Unvested at the end of the period (in dollars per share)	$ 4.93	$ 4.57
Total outstanding at the end of the period (in dollars per share)	$ 5.18	$ 5.14
Vested during year (in dollars per share)	$ 4.65
Weighted average remaining contractual life
Vested and exercisable	3 years 8 months 12 days	3 years 6 months
Unvested	8 years 4 months 24 days	7 years 8 months 12 days
Total outstanding	4 years 9 months 18 days	4 years 7 months 6 days