Arrangements with Off-Balance Sheet Risk - Narrative (Details)	9 Months Ended
	Sep. 30, 2017 USD ($)
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Outstanding surety bonds	$ 55,400,000
Guarantee obligations (up to)	$ 120,000,000.0
Standard warranty period	1 year
Line of Credit | Letter of Credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Outstanding commercial letters of credit	$ 39,100,000
Lenders named therein and Bank of America Merrill Lynch | Line of Credit | Letter of Credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Outstanding commercial letters of credit	$ 39,100,000