Fair Value Measurements (Contingent Purchase Price Consideration, Measured at Estimated Fair Value on Recurring Basis) (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Liabilities:
Warrants potentially settleable in cash	$ 14,528	$ 5,383
Unobservable Inputs (Level 3) [Member]
Liabilities:
Contingent purchase price consideration	6,972	6,651
Fair Value, Measurements, Recurring [Member]
Assets:
Cash equivalents	48,960	19,477
Total assets	48,960	19,477
Liabilities:
Warrants potentially settleable in cash	14,528	5,383
Contingent purchase price consideration	6,972	6,651
Total liabilities	21,500	12,034
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets (Level 1) [Member]
Assets:
Cash equivalents	48,960	19,477
Total assets	48,960	19,477
Liabilities:
Warrants potentially settleable in cash	0	0
Contingent purchase price consideration	0	0
Total liabilities	0	0
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Cash equivalents	0	0
Total assets	0	0
Liabilities:
Warrants potentially settleable in cash	14,528	5,383
Contingent purchase price consideration	0	0
Total liabilities	14,528	5,383
Fair Value, Measurements, Recurring [Member] | Unobservable Inputs (Level 3) [Member]
Assets:
Cash equivalents	0	0
Total assets	0	0
Liabilities:
Warrants potentially settleable in cash	0	0
Contingent purchase price consideration	6,972	6,651
Total liabilities	$ 6,972	$ 6,651