Earnings Per Share - Reconciliation (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Earnings Per Share [Abstract]
Numerator for basic and diluted EPS — net income allocated to common stockholders	$ 19,873	$ 1,797	$ 28,165	$ 30,902
Denominator for basic EPS — weighted average number of shares (shares)	30,046,450	29,792,997	30,326,050	30,094,986
Add — dilutive effect of:
Weighted average number of incremental shares issuable from restricted stock units (shares)	2,000	13,000	13,000	27,000
Denominator for diluted EPS — weighted average number of shares and dilutive potential shares (shares)	30,048,128	29,805,553	30,338,516	30,122,352
Earnings per share:
Basic (usd per share)	$ 0.66	$ 0.06	$ 0.93	$ 1.03
Diluted (usd per share)	$ 0.66	$ 0.06	$ 0.93	$ 1.03