Earnings Per Share (Basic and Diluted Earnings (Loss) Per Common Share) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Earnings Per Share [Abstract]
Net income attributable to common stockholders - Basic																	$ 36,178		$ 49,791		$ 26,540
Impact of assumed conversions:
Interest on convertible notes																	0		1,959		0
Dividends on preferred stock																	0		0		141
Net income attributable to common stockholders - Diluted																	$ 36,178		$ 51,750		$ 26,681
Weighted average common shares outstanding - Basic																	51,346		48,185		44,229
Assumed conversions:
Incremental common shares from warrants																	1,355		1,560		2,222
Incremental common shares from stock options																	1,133		992		747
Incremental common shares from convertible preferred stock before conversion																	0		0		440
Incremental common shares from restricted stock units																	7		116		0
Incremental common shares from convertible senior notes																	0		2,701		0
Weighted average common shares outstanding - Diluted																	53,841		53,554		47,638
Basic earnings per common share	$ 0.21	[1]	$ 0.17	[1]	$ 0.17	[1]	$ 0.16	[1]	$ 0.48	[1]	$ 0.20	[1]	$ 0.27	[1]	$ 0.08	[1]	$ 0.70	[1]	$ 1.03	[1]	$ 0.60
Diluted earnings per common share	$ 0.20	[1]	$ 0.16	[1]	$ 0.16	[1]	$ 0.15	[1]	$ 0.44	[1]	$ 0.19	[1]	$ 0.25	[1]	$ 0.07	[1]	$ 0.67	[1]	$ 0.97	[1]	$ 0.56

[1] The sum of the quarterly earnings per share (basic and diluted) may not agree to the earnings per share for the year due to the timing of common stock issuances.