Earnings Per Common Share (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Net Income attributed to:
Net income	$ 12,072	$ 11,870	$ 26,970	$ 23,676
Common stock
Net Income attributed to:
Net income	12,072	11,870	26,970	23,651
Participating restricted common stock
Net Income attributed to:
Net income				$ 25