Fair Value Measurements - Changes in Level 3 Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016		Dec. 31, 2015
Interest Rate Lock Commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets Beginning Balance		$ 9,161	[1],[2]	$ 7,576
Total Realized and Unrealized Gains (Losses), Assets		4,345	[2],[3],[4]	1,585	[5],[6]
Purchases and Issuances	[2],[7]	0
Sales and Settlements	[2]	(13,506)
Transfers In (Out)	[2]	0
Assets Ending Balance	[2]	0		9,161	[1]
Liabilities Beginning Balance		923		1,222
Total Realized and Unrealized Gains (Loss), Liabilities		923	[4],[8]	299
Liabilities Ending Balance		0		923
Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets Beginning Balance	[1]	157	[9]	193
Total Realized and Unrealized Gains (Losses), Assets		1	[3],[4],[9]	(36)	[1],[5],[6]
Purchases and Issuances		0	[7],[9]	0	[1],[10]
Sales and Settlements		0	[9]	0	[1]
Transfers In (Out)		0	[9]	0	[1]
Assets Ending Balance	[9]	158		157	[1]
Auction Rate Securities Purchase Commitment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets Beginning Balance	[9]	0
Total Realized and Unrealized Gains (Losses), Assets	[3],[4],[9]	849
Purchases and Issuances	[7],[9]	0
Sales and Settlements	[9]	0
Transfers In (Out)	[9]	0
Assets Ending Balance	[9]	849		0
Auction rate securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets Beginning Balance	[11],[12]	86,802	[13],[14]	91,422
Total Realized and Unrealized Gains (Losses), Assets		1,974	[3],[4],[13],[14]	1,955	[5],[6],[11],[12]
Purchases and Issuances		13,775	[7],[13],[14]	17,950	[10],[11],[12]
Sales and Settlements		(17,625)	[13],[14]	(24,525)	[11],[12]
Transfers In (Out)	[13],[14]	0
Assets Ending Balance	[13],[14]	84,926		86,802	[11],[12]
Auction Rate Securities Purchase Commitment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities Beginning Balance	[15]	1,369	[8]	902
Total Realized and Unrealized Gains (Loss), Liabilities	[4],[8],[9]	724		(467)
Liabilities Ending Balance	[8]	645		1,369	[15]
Municipal obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets Beginning Balance		81		164
Total Realized and Unrealized Gains (Losses), Assets		25	[3],[4]	(63)	[5],[6]
Purchases and Issuances	[7]	0
Sales and Settlements		(62)		(20)
Transfers In (Out)		0
Assets Ending Balance		$ 44		$ 81

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