Summary of Significant Accounting Policies - Narrative - Inventories (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
General and administrative costs incurred	$ 262.9	$ 273.9
General and administrative costs included in long-term contract inventories	$ 1.8	$ 3.8

The actual or estimated amount of general and administrative expense remaining in inventory as of the balance sheet date.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.6(b))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Name:	us-gaap_InventoryForLongTermContractsOrProgramsGeneralAndAdministrativeCostsIncludedInInventory
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant