Earnings Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Earnings per common share:
Net income attributable to common stockholders - Basic	$ 9,806	$ 17,917	$ 26,590	$ 25,549
Impact of assumed conversions:
Interest on convertible notes		867
Dividends on preferred stock				140
Net income attributable to common stockholders - Diluted	$ 10,220	$ 18,784	$ 26,590	$ 25,689
Weighted average common shares outstanding-Basic	48,384	47,178	48,054	43,201
Assumed conversions:
Incremental common shares from warrants	1,493	1,727	1,617	2,388
Incremental common shares from stock options	1,003	743	986	743
Incremental common shares from convertible preferred stock before conversion				581
Incremental common shares from restricted stock units	158
Incremental common shares from convertible senior notes	2,440	4,681
Weighted average common shares outstanding - Diluted	53,478	54,329	50,737	46,913
Basic earnings per common share	$ 0.20	$ 0.38	$ 0.55	$ 0.59
Diluted earnings per common share	$ 0.19	$ 0.35	$ 0.52	$ 0.55