Net (Loss) Income Per Share (Earnings Per Share) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Earnings Per Share [Abstract]
Net (loss) income	$ (15,997)	[1],[2]	$ (13,944)	[1],[3]	$ (5,299)	[1],[4]	$ (5,661)	[1]	$ 883	[5]	$ 434	[6]	$ (728)	[6]	$ (959)	[6]	$ (40,901)	$ (370)	$ 2,226
Historical common shares outstanding at beginning of year (excluding shares of unvested restricted stock)									41,208,096									41,208,096	34,839,131	33,883,378
Weighted average common shares issued																	471,273	4,101,413	493,469
Weighted average common shares outstanding-basic																	41,679,369	38,940,544	34,376,847
Effect of dilution from stock options																	0	0	1,390,123
Weighted average common shares outstanding-diluted																	41,679,369	38,940,544	35,766,970
Net (loss) income per share, basic (usd per share)	$ (0.38)	[1],[2],[7]	$ (0.33)	[1],[3],[7]	$ (0.13)	[1],[4],[7]	$ (0.14)	[1],[7]	$ 0.02	[5],[7]	$ 0.01	[6],[7]	$ (0.02)	[6],[7]	$ (0.03)	[6],[7]	$ (0.98)	$ (0.01)	$ 0.06
Net (loss) income per share, diluted (usd per share)	$ (0.38)	[1],[2],[7]	$ (0.33)	[1],[3],[7]	$ (0.13)	[1],[4],[7]	$ (0.14)	[1],[7]	$ 0.02	[5],[7]	$ 0.01	[6],[7]	$ (0.02)	[6],[7]	$ (0.03)	[6],[7]	$ (0.98)	$ (0.01)	$ 0.06

[1] During the first, second, third and fourth quarters of 2014, the Company incurred $0.3 million, $4.0 million, $3.8 million and $7.8 million, respectively, in transaction and integration costs related to the acquisition of AngioScore. See Note 2, “Business Combinations.”

[2] During the fourth quarter of 2014, the Company incurred $1.5 million in transaction costs related to the acquisition of the Stellarex DCB Assets. See Note 17, “Subsequent Event.”

[3] During the third quarter of 2014, the Company recorded an impairment charge of $4.1 million and a reduction of $1.1 million to the contingent consideration liability related to certain assets and liabilities recorded from the acquisition of Upstream in 2013. See Note 6, “Goodwill and Other Intangible Assets.”

[4] Net loss and net loss per share have been adjusted from the previously filed Form 10-Q as of June 30, 2014 to reflect adjustments made during the measurement period to provisional amounts recognized for the AngioScore acquisition at the acquisition date. The Company recorded a deferred tax benefit of $1.3 million related to a partial release of valuation allowance related to the AngioScore acquisition. See Note 14, “Income Taxes.”

[5] During the fourth quarter of 2013, the Company incurred $0.6 million of medical device excise tax expense, $0.2 million in contingent consideration expense, and $0.2 million in acquisition-related intangible asset amortization. In addition, during the fourth quarter of 2013, the Company recorded an intangible asset impairment of $4.5 million and an adjustment to the contingent consideration liability of $5.2 million related to certain assets and liabilities recorded from the acquisition of Upstream in 2013. See Note 6, “Goodwill and Other Intangible Assets.

[6] During each of the first, second and third quarters of 2013, the Company incurred $0.5 million of medical device excise tax (which commenced January 1, 2013), $0.2 million in contingent consideration expense, and $0.2 million in acquisition-related intangible asset amortization, respectively.

[7] The sum of the quarterly net income per share amounts may not total to each full year amount because these computations are made independently for each quarter and for the full year, and take into account the weighted average number of common stock equivalent shares outstanding for each period.