Earnings Per Share Earnings Per Share - Reconciliation (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Abstract]
Numerator for basic and diluted EPS — net income allocated to common stockholders	$ 1,797	$ 8,589	$ 30,902	$ 26,965
Denominator for basic EPS — weighted average number of shares (shares)	29,792,997	30,252,342	30,094,986	30,611,270
Add — dilutive effect of:
Weighted average number of incremental shares issuable from restricted stock units (shares)	12,555	8,466	27,366	7,567
Denominator for diluted EPS — weighted average number of shares and dilutive potential shares (shares)	29,805,553	30,260,808	30,122,352	30,618,837
Earnings per share:
Basic (usd per share)	$ 0.06	$ 0.28	$ 1.03	$ 0.88
Diluted (usd per share)	$ 0.06	$ 0.28	$ 1.03	$ 0.88