Earnings Per Share - Reconciliation (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Earnings Per Share [Abstract]
Numerator for basic and diluted EPS — net income allocated to common stockholders	$ 8,054	$ 15,487	$ 8,292	$ 29,104
Denominator for basic EPS — weighted average number of shares (shares)	29,954,291	29,912,161	30,218,513	30,131,291
Add — dilutive effect of:
Weighted average number of incremental shares issuable from restricted stock units (shares)	6,732	8,018	36,036	40,209
Denominator for diluted EPS — weighted average number of shares and dilutive potential shares (shares)	29,961,023	29,920,179	30,254,549	30,171,500
Earnings per share:
Basic (usd per share)	$ 0.27	$ 0.52	$ 0.27	$ 0.97
Diluted (usd per share)	$ 0.27	$ 0.52	$ 0.27	$ 0.96