Acquisitions - Summary of Fair Value Assets and Liabilities Assumed (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Cash	$ 206,364	$ 203,864	$ 152,154	$ 99,699
Goodwill	$ 87,543	87,543	$ 51,786
Clean Energy Experts, LLC
Business Acquisition [Line Items]
Cash		424
Accounts receivable		639
Intangible assets		13,290
Accounts payable and accrued liabilities		(1,247)
Deferred tax liability		(5,146)
Identifiable assets and liabilities assumed		7,960
Goodwill		35,757
Total		$ 43,717