Net Income Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Numerator:
Net income attributable to common stockholders	$ 12,167	$ 13,663	$ 26,960	$ 26,847
Net income allocated to participating securities	(11)	(16)	(30)	(37)
Numerator for basic net income per share	12,156	13,647	26,930	26,810
Numerator for diluted net income per share	13,258	15,397	28,032	30,310
Denominator:
Denominator for basic net income per share - weighted average outstanding common shares	86,793	76,900	81,964	76,834
Dilutive effect of stock options	9	0	4	0
Dilutive effect of contingently issuable shares	27	28	40	41
Denominator for diluted net income per share	95,653	87,530	86,444	87,477
Net income per share attributable to common stockholders - basic (in dollars per share)	$ 0.14	$ 0.18	$ 0.33	$ 0.35
Net income per share attributable to common stockholders - diluted (in dollars per share)	$ 0.14	$ 0.18	$ 0.32	$ 0.35
Series A Preferred Stock [Member]
Numerator:
Dividends on Preferred Stock	0	1,750	0	3,500
Denominator:
Dilutive effect of Preferred Stock	0	10,602	0	10,602
Series B Preferred Stock [Member]
Numerator:
Dividends on Preferred Stock	$ 1,102	$ 0	$ 1,102	$ 0
Denominator:
Dilutive effect of Preferred Stock	8,824	0	4,436	0