Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6907707&loc=SL6600010-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Unrecognized Tax Benefit
-URI http://asc.fasb.org/extlink&oid=6527854

Name:	us-gaap_UnrecognizedTaxBenefits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Summary of Significant Accounting Policies - Recently Adopted Accounting Standards (Details) - USD ($) $ in Thousands	Jan. 01, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Retained earnings		$ 536,350	$ 571,626
Unrecognized Tax Benefits		7,356	$ 15,553	$ 14,395	$ 13,074
ASU 2016-09
Unrecognized Tax Benefits		$ 0
ASU 2016-09 \| Subsequent Event
Retained earnings	$ (500)