Equity Incentive Plan - Summary of Restricted Share Awards (Details) (Restricted Stock, USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Restricted Stock
Summary of company's restricted share awards
Number of Shares, Nonvested at beginning of the period (in shares)	140,077	51,029
Number of Shares, Granted (in shares)	81,658	114,567
Number of Shares, Vested (in shares)	(60,217)	(25,519)
Number of Shares, Nonvested at end of the period (in shares)	161,518	140,077
Weighted - Average Grant Date Fair Value, Nonvested at beginning of the period (in dollars per share)	$ 12.70	$ 19.04
Weighted - Average Grant Date Fair Value, Granted (in dollars per share)	$ 13.43	$ 11.28
Weighted - Average Grant Date Fair Value, Vested (in dollars per share)	$ 15.26	$ 19.04
Weighted - Average Grant Date Fair Value, Nonvested at end of the period (in dollars per share)	$ 12.49	$ 12.70