Derivative Instruments (Effect of Derivatives on Consolidated Statements of Income) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Designated as Hedging Instrument [Member] | Fair Value Hedging [Member] | Interest rate contracts [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized gain on interest rate contracts	[1]	$ 413	$ 805	$ 1,534
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Interest rate contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in other comprehensive income, net of tax (effective portion)		(145)	916
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Interest rate contracts [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Loss reclassified from accumulated other comprehensive income (effective portion)	[1]	(149)	$ (215)
Derivatives not designated as Hedging Instrument [Member] | Lumber price contracts [Member] | Gain on Lumber Hedge [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized gain on lumber price swap		$ 1,088

[1] Realized gains and losses on interest rate contracts consist of net cash received or paid and interest accruals on the interest rate swaps during the periods. Net cash received or paid is included in the supplemental cash flow information within interest, net of amounts capitalized in the Consolidated Statements of Cash Flows